Three Historic Heatwaves

Summary

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Podcast Summary: Stuff You Missed in History Class

Episode: Three Historic Heatwaves
Hosts: Tracy V. Wilson & Holly Frey
Release Date: August 3, 2026
Podcast: iHeartPodcasts

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Overview

In this episode, Holly and Tracy explore three devastating heatwaves from European history, spanning the years 1540, 1757, and 2003. The hosts discuss the historical context, the wide-reaching impacts of extreme heat on society, science, and mortality, and highlight how heatwaves have often been overlooked in historical records compared to other natural disasters. The episode weaves together scientific insights, personal accounts, and memorable quotes, while drawing connections to modern climate change and societal responses.

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Main Discussion Points & Insights

1. Why Study Historical Heatwaves?

• Tracy introduces the topic, noting the comparative lack of focus on historic heatwaves, despite their deadly nature.

  “In a lot of the world today, heat waves just don't get as much attention as blizzards and floods and hurricanes, even though extreme heat is one of the deadliest weather events on average.” (Tracy, 03:14)

• She highlights the research challenge due to the scarcity of records and cultural minimization of heatwaves.

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2. The 1540 Central European Heatwave

[Starts at 04:35]

Historical Context: The Little Ice Age

• Occurred amid a period better known for cold and wet weather, yet Central Europe and northern Italy experienced a severe multi-year drought culminating in 1540.

Impacts and Eyewitness Accounts

• Rain Scarcity: Entire regions went weeks or months without rain; water sources dried up (Tracy, 06:02).
• Agricultural Collapse: “Crops failures and trees and other plants lost all of their leaves. Livestock had to be driven a lot farther to find water sources that weren’t totally depleted.” (Tracy, 06:45)
• Economic Disruption: With water-driven mills unusable, communities switched to horse-powered milling—inefficient and taxing on already weakened livestock (Holly, 07:10).
• Wine: Despite general crop failure, 1540 became a "millennium vintage" for wine because the harsh heat produced unique, sweet grapes (Tracy, 07:50).

Disease, Fire, and Social Unrest

• Disease spread by contaminated water when people resorted to dangerous sources; up to 500,000 may have died (Holly, 08:38).
• Fires: Massive blazes, including the destruction of Einbeck, Germany, killing hundreds. Fires were often blamed on arsonists, sometimes fueled by religious conflicts of the Protestant Reformation (Tracy, 10:03).
• No Thermometers: Quotes from Martin Luther lamented the “unspeakable and unrelenting” heat, but no precise temps are known as reliable thermometry didn't exist (Holly, 11:02).

Scientific Limitations

• Reliance today on proxy data (tree rings, pollen, modeling), but estimates of 1540’s temperatures versus modern records are debated (Holly, 12:22; Tracy, 12:54).
• Regions recovered rapidly due to drought-tolerant cropping traditions (Holly, 13:35).

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3. The 1757 Heatwave in the UK and Western Europe

[Starts at 17:28]

Advances in Temperature Measurement

• The 18th century saw the development of the modern thermometer—Gabriel Fahrenheit and Anders Celsius made temperature science standardized and reliable, allowing for specific record keeping (Holly, 18:15; Tracy, 19:04).

Eyewitness Reports & Data

• Doctor John Huxham wrote, “the heat was violent, greater than has been known here in the memory of man,” citing Plymouth shade temperatures of 87-88°F (30.5-31.1°C) in July (Holly, 21:27).
• Huxham detailed medical consequences:

  “Abundance of people have suffered very feverishly... Putrid, bilious, petechial, nervous fevers are exceedingly common everywhere. Dysenteries, hemorrhages… at most profuse sweats affect not only those in fevers, but a vast many others.” (Tracy, 22:17)

• Notable Quote from Horace Walpole, who wrote:

  “I have made the tour of my own garden but once these three days before eight at night. And then I thought I should have died of it. For how many years? We shall have to talk of the summer of 57.” (Tracy, 23:11)

Regional Variations

• Southern UK (e.g. Eddystone Lighthouse) reported milder weather, somewhat dismissing heat claims elsewhere (Tracy, 26:02).
• Scottish physician James Lind’s essay notes 80°F in Edinburgh on July 12 as “quite stifling” (Holly, 26:33).

Continental Europe and Aftermath

• France hit 99.5°F (37.5°C) in Paris (Tracy, 27:54).
• After 1757, Europe entered a cooling trend until the 20th-century warming.

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4. The 2003 European Heatwave

[Starts at 29:01]

Scale & Data

• Massive data collection enables detailed knowledge: temperatures 20-30% above average, with sustained high day and overnight temps from June to mid-August (Holly, 29:44).
• UK peaked at 38.1°C (100.58°F), Switzerland at 41.5°C (106.6°F); central/western Europe frequently saw 35-40°C (95-104°F) (Tracy, 30:13).

Human Toll

• The UN called it “Europe’s worst natural disaster in 50 years.” Death estimates range from 30,000 (UN) to 70,000 (various sources); 14,000+ deaths in France alone, disproportionately affecting elderly women living alone (Holly, 30:48).
• “So many people died in France that temporary morgues had to be set up using refrigerated trucks.” (Holly, 30:48)

Societal & Government Response

• French government created heat emergency plans, leading to sharply reduced heatwave fatalities in subsequent years (Tracy, 31:45).
• Broader urban policies: planting more trees, creating cooling centers, and legal obligations toward carbon neutrality.
• Comparative insight: Extreme heat is also the deadliest weather event in the US, with rising numbers despite prevalent air conditioning (Tracy, 31:45).

Other Effects

• Drowning deaths rose as people sought relief; in 2003, many victims were young men and boys (Holly, 33:08; Tracy, 33:39).
• Agriculture suffered shortages and losses similar to past events (fodder, grains, livestock).
• Over 20,000 forest fires burned 650,000 hectares; Alpine glaciers shrank up to 10%; thawing led to landslides (Tracy, 33:39).
• Power and hydrological infrastructure was challenged—dams and nuclear plants faced critical water shortages; France even shut down nuclear reactors due to low river coolants (Holly, 34:51).

Modern Context

• 2003’s records have since been broken: UK surpassed its heat record in 2022 (40.3°C/104.5°F), France in 2019 (45.9°C/114.6°F) (Tracy, 35:34).
• World Meteorological Association: “The last 11 years have been the 11 warmest on record. And June of 2026… was the hottest June on record ever in Western Europe.” (Tracy, 36:48)

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Notable Quotes & Memorable Moments

• On perspective:

  “It’s not a contest. We do not need to one up each other over the weather we have endured.” (Tracy, 03:56)

• Martin Luther on the 1540 Drought:

  “…the heat as unspeakable and unrelenting, and reads as though he is praying for the last day, meaning Judgment Day, so that that heat will be over.” (Holly, 11:02)

• On the spread of disease:

  “It is possible that as many as half a million people in Europe died of disease during this period, much of it spread through contaminated water.” (Holly, 08:38)

• On public health and climate:

  “…heat waves are a significant cause of death, especially in elderly people. In the United States, too, those deaths disproportionately affect the most vulnerable people. Extreme heat causes more fatalities on average than any other type of weather…” (Tracy, 31:45)

• Concluding with poetry:

  “…even now behold the grateful change at hand. Hark. In the east loud blustering gales arise… Let wonder, reverence, gratitude be mine.” (John Scott poem, read by Holly, 36:48)

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Timestamps for Important Segments

• Episode Theme & Rationale: 02:38 – 04:35
• 1540 European Heatwave: 04:35 – 14:05
• Development of Thermometers / Science: 17:28 – 20:47
• 1757 UK & Europe Heatwave: 20:47 – 28:47
• 2003 European Heatwave & Modern Warming: 29:01 – 36:48
• John Scott Poem & Wrap-Up: 36:48 – 37:33

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Tone and Style

• The tone is conversational, accessible, and historically grounded, balancing dry facts with occasional humor and empathy.
• The hosts frequently provide context and caveats, gently guiding listeners through biases and limitations in historical and scientific records.
• They emphasize empathy, public health, and the dangers of minimizing the seriousness of historic and contemporary heatwaves.

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Key Takeaways

• Extreme heat has been a recurring and deadly force in European history, impacting food supply, health, infrastructure, and society.
• Historical records can be incomplete, requiring reliance on proxy data and new modeling.
• Societal responses to heatwaves—past and present—have shaped outcomes, and learning from the past is crucial as the planet warms.
• Public health, social structures, and infrastructure adaptation are vital to reducing harm from extreme weather events.

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This episode offers a deep, engaging look at three transformative periods of extreme heat in Europe, skillfully balancing science, social history, lived experience, and ongoing relevance as climate extremes become increasingly common.

Transcript

[Tracy V. Wilson]

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[Holly Frey]

Welcome to Stuff youf Missed in History Class, a production of iHeartrad.

[Tracy V. Wilson]

Hello and welcome to the podcast. I'm Tracy V. Wilson.

[Holly Frey]

And I'm Holly Fry.

[Tracy V. Wilson]

For a while now, like years in the wake of years of rising temperatures, seemingly every summer being hotter than the one before, or at least as hot heat waves all over the world. I've really wanted to do some kind of episode about a historical heat wave. And I've written episodes over the years of doing this show about other weather phenomena and other natural disasters, like Hurricane San Siriaco, the Schoolhouse Blizzard, the Long Winter, the Vanport Flood, the Year Without a Summer, various earthquakes and fires and tsunamis and volcanic eruptions. We've got a lot of this in the archive, but never anything about a heat wave. In a lot of the world today, heat waves just don't get as much attention as blizzards and floods and hurricanes, even though extreme heat is one of the deadliest weather events on average. And that is actually true in a lot of historical writing as well. I had a wealth of resources to draw from on all of those other episodes that I just mentioned, but getting the information together about heat waves from the past turned out to be a lot trickier. So instead of doing one episode about one heat wave, which is what I was planning when I started this, we are going to take a shorter look at three of them. As a note, it is very possible that when we mention specific temperatures in this episode, your first thought might be that is not that hot. It's not that hot for some of the places that I have lived, it was unusually hot for the places that we are talking about in the time that those temperatures were happening. Uh, it's not a contest. We do not need to one up each other over the weather we have endured.

[Holly Frey]

And our first historical heat wave was not just a heat wave. It was part of a massive, severe drought that affected much of Central Europe as well as northern Italy. Perhaps surprisingly, this was during the period of regional cooling known as the Little Ice Age, during which parts of the world, including parts of Europe, generally saw cooler, wetter weather, including the expansion of glaciers. Depending on the source and what criteria they're using to define it, the Little Ice Age lasted from about 1500 to 1850 or from the end of the Medieval Warming period. So from about 1300 to 1850.

[Tracy V. Wilson]

Yeah. The little Ice Age was complicated, though. I feel like even 20 years ago, it was kind of being described as this global period of cooling. But it really did not mean that the whole world, or even just all of Europe, was consistently colder. It would be more accurate to say that a lot of the world saw more variable and sometimes more extreme weather overall in multiple directions during the Little Ice Age. In some areas, the cooler weather was accompanied by periods of drought rather than being wetter. But in Central Europe and Northern Italy, the weather was both warmer and drier, particularly from 1531 to 1540. There were multiple summer droughts during those 10 years.

[Holly Frey]

An intense period of drought started in February of 1540, and it lasted for about 11 months. There are hundreds of written accounts of the weather and its effects during that year, but since they're overwhelmingly written in other languages, we're not going to try to read directly from them. In parts of the affected regions, surviving accounts from 1540 describe no rain at all or negligible rain for weeks or even months at a time. Water became scarce as wells and springs dried up and water levels fell in lakes, rivers and streams. Accounts from all over Central Europe describe the ground becoming desiccated.

[Tracy V. Wilson]

This lack of water had far reaching effects, of course. There were crop failures and trees and other plants lost all of their leaves. Livestock had to be driven a lot farther to find water sources that weren't totally depleted. And there were shortages of fodder to feed those animals because the fodder crops failed. So all of that contributed to a lot of livestock deaths.

[Holly Frey]

Water was also a major source of power, with rivers powering water wheels that were used to mill grain. Without enough water in the rivers, people turned to mills that were powered by horses. But those horses also needed food and water and could become overheated as they worked. People could grind grain for their own use using hand mills, but that wasn't really something that worked at large scale, especially with people facing the same heat and water shortages that the stock animals were. Rivers were also a major transportation route for people and goods. And in a lot of areas, that whole transportation system just shut down.

[Tracy V. Wilson]

While the drought led a lot of crops to die in the fields, in some parts of Europe, 1540 became an exceptionally good wine year. A lot of vineyards tried to adjust their harvest based on the weather conditions. They either harvested early or they left fruit on the vine later than normal, hoping that another rainfall would come and would make the fruit juicier. At some vineyards around the Alsace region, the harvest was partial because some of the grapes had basically dried into raisins and just couldn't be salvaged in places that delayed the harvest, but did wind up with harvestable fruit. The resulting overly mature grapes turned into a wine that was very sweet. And 1540 wound up being described as a millennium vintage.

[Holly Frey]

It's likely that the lack of water contributed to the spread of illness. People did not have enough water to wash themselves or their environments. Some places actually banned doing laundry during the driest weeks. As wells dried up, people got water from sources that were likely to be contaminated, including rivers that had become sluggish and stagnant. The lack of rain meant that contaminants that would have been washed away or at least diluted in a typical year stayed around. There was an epidemic of dysentery, and it is possible that as many as half a million people in Europe died of disease during this period, much of it spread through contaminated water.

[Tracy V. Wilson]

Fire was also a serious problem. In July, Martin Luther wrote a letter to his wife about forest fires in Germany that had burned at that time more than a thousand acres, and he thought that would probably make timber more expensive. There were also forest fires in the Vosges Mountains in eastern France and in Hungary and Poland.

[Holly Frey]

Fires also struck villages and towns, and some of them burned down entire communities. That included Einbeck in central Germany, which was entirely destroyed on July 26, 1540. Hundreds of people were killed in that fire. Estimates range from 100 to 500, especially

[Tracy V. Wilson]

in towns and villages. This spike in fires led to accusations of arson, and at least some of those accusations were connected to the changes that European societies were going through in the 16th century. The start of the Protestant Reformation is generally marked as Martin luther posting his 95 theses at the Castle Church in Wittenberg, Germany, on October 31, 1517. Conflict between Protestants and Catholics was ongoing in 1540, and in Germany, Duke Einrich the Younger was accused of hiring arsonists to burn down Protestant communities. In other areas. Anabaptists, who were facing religious persecution, were the ones who were blamed for starting the fires. Most of these fires were probably accidental and just a byproduct of how dry everything was and how little water there was to fight them.

[Holly Frey]

There are lots of written records describing the lack of water, the crop failures, illnesses and fires in 1540, and there are written descriptions of the heat. Another letter from Martin Luther to his wife that summer describes the heat as unspeakable and unrelenting, and reads as though he is praying for the last day, meaning Judgment day, so that that heat will be over. But we don't have anyone's firsthand accounts of the actual temperature because modern thermometers did not exist yet.

[Tracy V. Wilson]

The earliest known thermometer like device was described by Philo of Byzantium in the third century bce. This was a hollow lead bulb attached to a tube, with the end of the tube submerged in water. When the bulb was heated, the air in it would expand and bubbles would come out of the end of the tube through the water. When the bulb cooled down, water would then be drawn up into the tube from the vessel. But there was not any kind of a scale attached to this. It was just a way to illustrate that the volume of air expands when it's heated and contracts when it cools, and then that corresponds to changes in temperature. It was not a precise method of measuring air temperature by any stretch.

[Holly Frey]

So while we do have lots of general descriptions of what life was like, we don't have exact numbers of how hot the summer of 1540 was in central Europe. Our knowledge of that comes from proxy data, things like ice cores, tree rings, and pollen samples combined with modeling techniques. But even with those sources of data, there is debate about exactly how high the temperatures reach during this event, specifically whether they were higher or lower than more modern day temperature records.

[Tracy V. Wilson]

A frequently used benchmark in a lot of writings about this is the summer of 2003, which when it happened, was described as the hottest summer in parts of Europe in 500 years. Different researchers have concluded that the summer of 1540 was either below or above the high temperatures that were recorded in the summer of 2003. Sort of depends on exactly how they're modeling. Some researchers have also noted that the summer of 1540 was so extreme that typical climate models can't really replicate it without changing the parameters in a way that go way beyond other known extreme weather events.

[Holly Frey]

It is also difficult to determine how many people died or became disabled as a result of this heat wave and drought. But it seems like the regions that were affected recovered fairly quickly after it subsided, in part because people already preferred to grow crops that could be drought tolerant. So once the weather started to cool and new crops were planted and water levels returned toward normal, people were able to grow, harvest and mill much like they could before.

[Tracy V. Wilson]

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[Tracy V. Wilson]

Our next heat wave took place in the UK and Western Europe in 1757. By that point, there were thermometers that could be used to more precisely measure the temperature. This built on the work of Philo of Byzantium. It's believed that Galileo developed a thermoscope that was somewhat similar to Philo's in the early 1600s. Other 17th century scholars did this as well, and some also developed a calibration system for their thermoscopes to approximate some kind of measurement. One was Italian physiologist Santorio Santorio, who made a thermoscope that was designed to go in the mouth. He could then use that to measure a person's body temperature.

[Holly Frey]

Physician and instrument maker Gabriel Fahrenheit developed the Mercury in glass thermometer in 1714, and he developed his Fahrenheit temperature scale ten years later. Swedish astronomer and physicist Anders Celsius and others started advocating for an internationally recognized temperature scale in the 1740s, leading to the Celsius, or Centigrade scale. Celsius is often credited with inventing this scale, but his original 1742 version placed the freezing point of water at 100 degrees and the boiling point at zero. So opposite of how we know it today. Others flipped those values so that the boiling point was 100 and made mercury thermometers that were calibrated to that same scale.

[Tracy V. Wilson]

Yeah, it's not fully clear whether some of the people who were writing about temperature measurement around this time were working from Celsius's work, or if they independently arrived at the idea of a scale that goes from the boiling point to the freezing point of water. It could be either one. While we have more specific information about how hot it was in the summer of 1757, that information is still somewhat sporadic. Mercury thermometers and the Fahrenheit and Celsius scales were obviously very new. And it was new enough that a lot of the English language writing about this heat wave does not just say that people were using a thermometer. They all say Fahrenheit's thermometer. Specifically, people understood that they would get the most accurate readings on this thermometer if it was in the shade rather than in direct sunlight. But it's not always clear how well people protected their thermometer from the sun or whether their readings were inflated because the thermometer was not adequately protected or maybe was very close to something that was getting more direct sunlight.

[Holly Frey]

There was also no way to continuously record the temperature. People had to look at the thermometer and write it down. Some of the people who wrote about the heat in July of 1757 noted that they took their measurement at three in the afternoon. That was probably during the hottest part of the day, but it's not possible to know whether it got hotter before or after someone took their measurement. Regular, reliable, official temperature records didn't start in much of the world until the mid to late 19th century.

[Tracy V. Wilson]

A lot of the written documentation of the 1540 drought and heat wave is in the form of personal and business letters, diaries, chronicles, and in the case of those arson allegations, court records. By the 18th century, though, the European scientific community had started establishing scientific journals. The first was Philosophical Transactions, which was established in March of 1665 by Henry Oldenburg, who was secretary of the Royal Society. Philosophical Transactions documented the Royal Society's activities, including letters and papers that were read before Royal Society meetings.

[Holly Frey]

Some of these letters were between John Huxham and William Watson, who were both medical doctors and Royal Society fellows. Huxham wrote to Watson on July 19, 1757, saying in part, quote, from the 7th to the 14th of this month, the heat was violent, greater indeed than has been known here in the memory of man. I have talked with several persons who have lived considerable time in Jamaica, Gibraltar and Menorca, and they generally assert that they never felt such intense heat in any of those places. Huxham went on to say that in the shade, Fahrenheit's thermometer read 87 degrees at 3 in the afternoon on the 11th and 13th of July, and that it was above 88 on the 12th. That's about 30.5 and 31.1 degrees Celsius.

[Tracy V. Wilson]

Huxham continued, quote, abundance of people have suffered very feverishly from these excessive heats. Putrid, bilious, petechial, nervous fevers are exceedingly common everywhere. Dysenteries, hemorrhages, at most profuse sweats affect not only those in fevers, but a vast many others. He described both the days and the nights as intolerably hot, with people unable to sleep and the wind even blowing hot, so that it brought no relief.

[Holly Frey]

This publication in Philosophical Transactions also included a note from Watson with a table of temperatures recorded in Plymouth using Fahrenheit's thermometer. The temperatures were in the 80s from July 10th to 15th, with a peak of 85 on July 14th. That's about 29.4 degrees Celsius.

[Tracy V. Wilson]

Yeah. The temperatures that people would have been expecting in these areas at this point point would have been more in the high 70s. On July 12, past podcast subject Horace Walpole wrote a letter to his friend John Chute about his willingness to visit Chute at his estate in Hampshire, known as the Vine. Quote, I say nothing of the heat of this magnificent weather, with the glass Yesterday up to 3/4 of sultry. In all English probability, this will not be a hindrance long, though at present, so far from traveling, I have made the tour of my own garden but once these three days before eight at night. And then I thought I should have died of it. For how many years? We shall have to talk of the summer of 57.

[Holly Frey]

A few days later, on the 16th, Walpole wrote a letter to George Montague saying, quote, the weather has been so hot and we are so unused to it that nobody knew how to behave themselves. Even Mr. Bentley has done shivering. That was writer Richard Bentley, who was part of Walpole's Committee of Taste along with Shute. A letter Walpole sent to Shute 10 days later described Bentley as suffering from sweating sickness, quote, which I now firmly believe was only a hot summer like this, and England, being so unused to it, took it for a malady.

[Tracy V. Wilson]

The heat returned that August, and John Huxham wrote to William Watson again. This letter was also published in Philosophical Transactions. This time Huxham said that his thermometer read almost 86 degrees, or 30 Celsius from August 8th through the 10th. This time he wrote, quote, the consequences of this extremely hot season were hemorrhages from several parts of the body. The nose, especially in men and children, and the uterus in women. Sudden and violent pains of the head and vertigo, profuse sweats, great debility and oppression of the spirits affected many. There were putrid fevers in great abundance and a vast quantity of fluxes of the belly, both bilious and bloody, with which the fevers also were commonly attended.

[Holly Frey]

Huxham described these fevers as accompanied by severe pains in the back and stomach, vomiting, chest pain, anxiety, and an inability to sleep. At this point, medicine in Europe was still largely dominated by the idea of the four humors. And from there he describes the quality of the pulse in people who were affected and their blood, which was, quote, oftentimes florid, but loose, sometimes livid, very rarely fizzy. He thought bloodletting was always beneficial, especially if it was done early in people who developed this heat related Fever.

[Tracy V. Wilson]

It seems as though the weather was milder off the southern coast of the uk. John Smeaton also wrote a letter that was read before the Royal Society about conditions at Eddystone Lighthouse, south of Plymouth. He said that the weather had been very moderate there in July, sometimes even cold for the season. I read this letter as like, weirdly braggy and doubting the accuracy of other people's reports of intense, unbearable heat.

[Holly Frey]

Gosh, it's terrific here. We actually need to wear sweaters. Scottish physician James Lind, who is most well known for his recommendation that citrus could be used to prevent scurvy in sailors, published an essay on the most effectual means of preserving the health of seamen in the Royal Navy in 1744. A section of its appendix is called Comparative Degrees of Heat and Cold in Different Latitudes, and among other things, it describes typical temperatures in Edinburgh and what it was like in the summer of 1757. He wrote, in the warmest weather in June, July and August, the Mercury was commonly at 70 in the middle of the day and 64 in the night. But during uncommon heats it has risen to 73 and 75 perhaps once or twice in a year, and sometimes not in two years. The greatest heat observed by the instrument There was on 12 July 1757, when, in the middle of the day and well shaded, it mounted to 80 degrees. The heat was then quite stifling. 70 degrees Fahrenheit is about 21.1 degrees Celsius, 75 is about 23.8 and 80 Fahrenheit is roughly 26.6 degrees Celsius.

[Tracy V. Wilson]

Temperatures spiked in France in the summer of 1757 as well, with a recorded high of 99.5 degrees Fahrenheit, or 37.5 Celsius. That was reported in Paris on July 14. But beyond the general description repeated in a lot of places of the hottest summer since 1540, I just did not find a lot of specific information about the heat wave's death toll or other effects. It does seem like, on average, temperatures in Europe started to cool after 1757, and that cooling trend continued until just after the start of the 20th century. One model shows 1902 as the coolest European summer in the last 500 years. But then, of course, things really started to heat up again, and we will

[Holly Frey]

talk about some of that heat after we pause for a sponsor break.

[Tracy V. Wilson]

Our last heat wave today is more recent than what we typically talk about on the show. When I started working on this episode, my whole plan was for it to be only about the July heat wave of 1757. And then I realized I just did not have enough information to do a whole episode only on that. But that summer is usually described as the hottest1 from 1540 to 2003. Sometimes 1540 and 2003 are presented almost like brackets around the summer of 1757. So once I decided to talk about 1540, it made sense to talk about that more recent one as well.

[Holly Frey]

And there is, of course, way more Data about the 2003 heat wave than the other two that we've talked about today. Thanks to a massive network of weather monitoring stations and the ability to process and evaluate data, we know that the summer of 2003 saw temperatures in Europe that were often between 20 and 30% higher than average. Overnight temperatures were often higher than the typical high during the day, and these conditions lasted from June to mid August.

[Tracy V. Wilson]

The highest recorded temperature in the UK during this heat wave was 38.1 Celsius, or 100.58 Fahrenheit. And that was at the time the highest temperature ever recorded in the U.K. switzerland set a record of 41.5 Celsius, or 106.6. Temperatures in Central and Western Europe were around 35 to 40 degrees Celsius, or 95 to 104 Fahrenheit, repeatedly over the course of this heat wave.

[Holly Frey]

According to the UN Environment Program, this heat wave was Europe's worst natural disaster in 50 years and one of the 10 deadliest over the previous century. Its Environment Alert bulletin about the heat wave estimated that the death toll would be more than 30,000. There were more than 14,000 deaths in France alone, disproportionately in Paris. Many of the people who died were elderly, and the most vulnerable group in France was elderly women who were living alone. So many people died in France that temporary morgues had to be set up using refrigerated trucks. Some other sources report even higher numbers for the total death toll, as many as 70,000 across Europe. A major factor was the fact that a lot of homes and public buildings in this part of Europe are not air conditioned, especially if they're historic structures rather than newly built.

[Tracy V. Wilson]

So before anybody gets on their high horse about air conditioning discourse, which there has been a lot of this summer, a lot of it with Americans making it sound like we're superior because of our very prevalent air conditioning, heat waves are a significant cause of death, especially in elderly people. In the United States, too, those deaths disproportionately affect the most vulnerable people. Extreme heat causes more Fatalities on average than any other type of weather in the United States. And those numbers in the US are rising, not falling. But after the 2003 heat wave, which was so devastating in France, the French government established an emergency plan for extreme heat events, which includes providing cooling spaces and water checking on vulnerable people. And there's also been ongoing work to plant more trees and provide more shade in public places, and to get more air conditioning installed, including in medical facilities. More broadly, France is legally bound to reach carbon neutrality by 2050, which is, of course, part of the effort to slow the rate of global warming. So the number of heat related deaths in France has been much smaller in heat waves that have taken place since 2003. And since these plans were created.

[Holly Frey]

In addition to the deaths that were directly related to the heat, another major cause of death in some parts of Europe during the 2003 heat wave was drowning. This has been true in other heat waves as well. Authorities in Germany reported that nearly 100 people drowned in June of 2026, while France reported 40 deaths from drowning in that heat wave. Officials in both countries compared that number to the number of people who had drowned during the heat wave of 2003.

[Tracy V. Wilson]

Yeah, there was a lot of. We have not seen numbers like this since 2003. Unlike the people who were most at risk of, like, direct heat related causes, who tended to be older people, a lot of the people who drowned were young people, especially boys and young men, who, of course, were just trying to cool off. The heat wave and the drought that it was part of in 2003 also, of course, affected agriculture and industry. And a lot of that was really similar to what we talked about happening back in 1540. Central Europe faced fodder shortages as those crops were depleted. Production also dropped for poultry and potatoes and grains. Forest fires were widespread, and they were exacerbated by the dry conditions and water stress on the trees. There were more than 20,000 fires across the affected parts of Europe, and that burned almost 650,000 hectares of forest. According to the World Glacier Monitoring Service, Alpine glaciers decreased by up to 10% in 2003. Thawing in mountainous areas also destabilized the landscape, and that led to landslides and rock slides.

[Holly Frey]

We talked about how the 1540 drought affected things like grain mills, which were powered by water wheels. Although fewer industries are powered in this way today, water is critical to the production of electricity, both through hydropower plants and in providing cooling for the other types of power plants. In France, some nuclear reactors had to be shut down in 2003 because there wasn't enough water available to cool them and others had to keep running even though the temperature of the available water exceeded safe levels. This led to power shortages, which were made worse by the spike in demand for things like refrigerators and air conditioning.

[Tracy V. Wilson]

As we said earlier, there's some debate about whether the 2003 heat wave and drought were worse than the one in 1540. I read multiple papers on this when preparing this episode. We do know, however, that subsequent years have been hotter than 2003 was. The UK record from the 2003 heat wave was broken in 2022 when temperatures in England reached 40.3 Celsius, or 104.5 Fahrenheit. On June 28, 2019, temperatures in France reached 45.9 Celsius, or 114.6 Fahrenheit. That broke its 2003 heat wave record by almost 2 degrees Celsius. This was the first time a temperature higher than 45 Celsius was ever recorded in France. According to the World Meteorological association, the last 11 years have been the 11 warmest years on record. And June of 2026, which of course was part of the inspiration for this episode, was the hottest June on record ever in Western Europe.

[Holly Frey]

We will end with a passage from John Scott from his poem written in the Hot Weather, July 1757. This was published in his 1764 Elegies, Descriptive and Moral. And this is from the end of the poem when the heat wave is about to break even now behold the grateful change at hand. Hark. In the east loud blustering gales arise wide and more wide the darkening clouds expand and distant lightning slash along the skies. Oh, in the awful concert of the storm, While hail and rain and wind and thunder join, Let the great rulers praise my song in form. Let wonder, reverence, gratitude be mine.

[Tracy V. Wilson]

I picked that part from the whole poem because it's the part that has a sense of relief from the heat coming. And that is three historic heat waves

[Holly Frey]

do you have a sense of listener mail coming?

[Tracy V. Wilson]

I do have some listener mail. This listener mail is from Katie. Katie wrote after we talked about the Bunker Hill Monument and the Battle of Bunker Hill and said hello ladies. I just listened to your Bunker Hill episode and was so happy that you said Bill Ricka correctly. I've been waiting for the perfect moment to send a note to you and this was perfect. I grew up in Boston and have always been a Revolutionary War nerd. Maybe not by choice, but by environment. Anyways, with all that is happening with the country I have to say, it makes it hard for me to be excited for the 250th. When I saw this episode, I said, yay, Boston. And I think listening to pods like yours and being conscious of how I am acknowledging the 250th is the way to go. Current plan for the 4th, listening to Hamilton, making a green reflecting pool cocktail and making crafts that incorporate my new mantra, crush garlic and the patriarchy. For my pet tax. I present to you my two boys, Maverick cat and fettuccine snake. Maverick is a wild goblin that shreds my boxes and my sanity, but redeems himself with very good snuggles. Fettuccine. My yellow noodle is a ball python and much more of a laid back little guy. Maverick would love to be friends, but my tank is incredibly cat proof. Thank you for being the best moral compass and saying what I am thinking about the state of things. And then we have just some adorable animal pictures.

[Holly Frey]

I love a ball python. I think they have the cutest faces.

[Tracy V. Wilson]

Yeah.

[Holly Frey]

Yeah. They just look sort of sweet.

[Tracy V. Wilson]

There are a lot of snakes that have very cute faces. And I have recently. This doesn't have anything to do with the episode or even the email. I have recently learned that there are people who work in areas that have a lot of venomous snakes to help train dogs to detect and avoid those snakes. And so they put a little muzzle on the rattlesnake. It's a very soft thing. The snake can still drink, still use their tongue, but they cannot open their mouth enough for their fangs to pop out.

[Holly Frey]

Gotcha.

[Tracy V. Wilson]

And so then that way the dog can smell and see and react to the snake without either of them being in danger. And then people who do this in a reputable way also only do this for a limited amount of time, so they're not stressing the snake out too much.

[Holly Frey]

Right.

[Tracy V. Wilson]

And then the dogs learn not to go sniff at that thing and then get bitten on the nose. And you're at the veterinary emergency room to get snake bite treatment.

[Holly Frey]

Anyway, I have to say, fettuccine is a brilliant name.

[Tracy V. Wilson]

It's a great name.

[Holly Frey]

And now I'm like, has anyone ever named a snake Alfredo Linguini? Maybe to get a little ratatouille reference in. Maybe just thinking about it.

[Tracy V. Wilson]

And then we do also have a picture of this craft project of crush some garlic and the patriarchy. I love it. Thank you so much, Katie. If you would like to send us a note, we're at history [e-mail] if you would like to find the show notes to our episodes where you can read all of the research that I used to prepare this that is at our website, which is missing and you can subscribe to the show on the iHeartRadio app or anywhere else you like to get your podcasts. Stuff youf Missed in History Class is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. This is an iHeart podcast. Guaranteed Human.