Recent blistering hot spells in Texas, the Pacific northwest and Europe have only served to amplify the belief that heat waves are now more frequent and longer than in the past, due to climate change. But a careful look at the evidence reveals that this belief is mistaken, and that current heat waves are no more linked to global warming than any of the other weather extremes we’ve examined.

It’s true that a warming world is likely to make heat waves more common. By definition, heat waves are periods of abnormally hot weather, last­ing from days to weeks. However, heat waves have been a regular feature of Earth’s climate for at least as long as recorded history, and heat waves of the last few decades pale in comparison to those of the 1930s – a period whose importance is frequently downplayed by the media and climate activists.

Those who dismiss the 1930s justify their position by claiming that the searing heat was confined to just 10 of the Great Plains states in the U.S. and caused by Dust Bowl drought. But this simply isn’t so. The evidence shows that the record heat of the 1930s – when the globe was also warming – extended throughout much of North America, as well as other countries such as France, India and Australia.

In the summer of 1930 two record-setting, back-to-back scorchers, each lasting 8 days, afflicted Washington, D.C. in late July and early August. During that time, 11 days in the capital city saw maximum temperatures above 38 Degrees Celsius (100 degrees Fahrenheit). Nearby Harrisonburg, Virginia roasted in July and August also, experiencing its longest heat wave on record, lasting 23 days, with 10 days of 38 Degrees Celsius (100 degrees Fahrenheit) or more.

In April the same year, an historic 6-day heat wave enveloped the whole eastern and part of the central U.S., as depicted in the figure below, which shows sample maximum temperatures for selected cities over that period. The accompanying excerpt from a New York Times article chronicles heat events in New York that July.

The hottest years of the 1930s heat waves in the U.S. were 1934 and 1936. Typical newspaper articles from those two extraordinarily hot years are set out below.

The Western Argus article on the left reports how the Dust Bowl state of Oklahoma in 1934 endured an incredible 36 successive days on which the mercury exceeded 38 degrees Celsius (100 degrees Fahrenheit) in central Oklahoma. On August 7, the temperature there climbed to a sizzling 47 degrees Celsius (117 degrees Fahrenheit). And in the Midwest, Chicago and Detroit, both cities for which readings of 32 degrees Celsius (90 degrees Fahrenheit) are normally considered uncomfortably hot, registered over 40 degrees Celsius (104 degrees Fahrenheit) the same day.

It was worse in other cities. In the summer of 1934, Fort Smith, Arkansas recorded an unbelievable 53 consecutive days with maximum temperatures of 38 degrees Celsius (100 degrees Fahrenheit) or higher. Topeka, Kansas, had 47 days, Oklahoma City had 45 days and Columbia, Missouri had 34 days when the mercury reached or passed that level. Approximately 800 deaths were attributed to the widespread heat wave.

In a 13-day heat wave in July, 1936, the Canadian province of Ontario – well removed from the Great Plains where the Dust Bowl was concentrated – saw the thermometer soar above 44 degrees Celsius (111 degrees Fahrenheit) during the longest, deadliest Canadian heat wave on record. The Toronto Star article on the right above describes conditions during that heat wave in normally temperate Toronto, Ontario’s capital. As reported:

a great mass of the children of the poverty-stricken districts of Toronto are today experiencing some of the horrors of Dante’s Inferno.

and, in a headline,

            Egg[s] Fried on Pavement – Crops Scorched and Highways Bulged      

Portrayed in the next figure are two scenes from the 1936 U.S. heat wave; the one on the left shows children cooling off in New York City on July 9, while the one on the right shows ice being delivered to a crowd in Kansas City, Missouri in August.

Not only did farmers suffer and infrastructure wilt in the 1936 heat waves, but thousands died from heatstroke and other hot-weather ailments. By some estimates, over 5,000 excess deaths from the heat occurred that year in the U.S. and another 1,000 or more in Canada; a few details appear in the two newspaper articles on the right below, from the Argus-Press and Bend Bulletin, respectively.

The article on the left above from the Telegraph-Herald documents the effect of the July 1936 heat wave on the Midwest state of Iowa, which endured 12 successive days of sweltering heat. The article remarks that the 1936 heat wave topped the previous one in 1934, when the mercury reached or exceeded the 38 degrees Celsius (100 degrees Fahrenheit) mark for 8 consecutive days.

Heat waves lasting a week or longer in the 1930s were not confined to North America; the Southern Hemisphere baked too. Adelaide on Australia’s south coast experienced a heat wave at least 11 days long in 1930, and Perth on the west coast saw a 10-day spell in 1933, as described in the articles below from the Register News and Longreach Leader, respectively.

Not to be outdone, 1935 saw heat waves elsewhere in the world. The adjacent three excerpts from Australian newspapers recorded heat waves that year in India, France and Italy, although there is no information about their duration; the papers were the Canberra Times, the Sydney Morning Herald and the Daily News.  But 1935 wasn’t the only 1930s heat wave in France. In August 1930, Australian and New Zealand (and presumably French) newspapers recounted a French heat wave earlier that year, in which the temperature soared to a staggering 50 degrees Celsius (122 degrees Fahrenheit) in the Loire valley – besting a purported record of 46 degrees Celsius (115 degrees Fahrenheit) set in southern France in 2019.  

Many more examples exist of the exceptionally hot 1930s all over the globe. Even with modern global warming, there’s nothing unusual about current heat waves, either in frequency or duration.

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