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With an extended period of 90 degree heat looming, we all will find ways of coping with the steam. As tough as it can be in this day and age, imagine what the blistering heat wave of July of 1936 was like. Electricity (and especially air conditioning) was still in its infancy when the hottest temperatures ever measured baked the Midwest. Here's a recap of the event from Christopher Burt the author of Extreme Weather; A Guide and Record Book. He studied meteorology at the University of Wisconsin-Madison.

Every summer some region of the U.S. experiences a “record-breaking” heat wave, as occurred earlier this summer in northern New England, Quebec, and California. But the most intense and widespread heat wave (actually a series of heat waves) ever recorded in the U.S. occurred during the summer of 1936, when 17 of the 48 contiguous U.S. states and two provinces of Canada tied or broke their all-time heat records, along with hundreds of cities. Many of these records stand today. Although we have some clues, it is ultimately a bit of a mystery as to what exactly caused the temperatures to spike so high that summer.

The climatological summer (June-August) of 1936 remains the warmest nationwide on record (since 1895) with an average temperature of 74.0°F. (The second warmest summer was that of 2012 with an average of 73.7°F.) July 1936 is still the single warmest U.S. month ever measured, with an average temperature of 76.8°F beating out July 2012 by just 0.02°F.

Interestingly, February 1936 remains the coldest February on record for the contiguous U.S., with an average nationwide temperature of 25.2°F. (The single coldest month on record was January 1977, with a 21.9°F average.) Temperatures fell as low as –60°F in North Dakota, an all-time state record. Turtle Lake, North Dakota averaged –19.4°F for the entire month, the coldest average temperature ever recorded in the contiguous United States for any month. One town in North Dakota, Langdon, stayed below 0°F for 41 consecutive days (from January 11 to February 20), the longest stretch below zero (including maximum temperatures) ever endured at any site in the lower 48.

With this in mind, it is truly astonishing what occurred the following summer. In North Dakota, where temperatures had dipped to –60°F on February 15, 1936, at Parshall, it hit 121°F at Steele by July 6. The two towns are just 110 miles from one another!

June of 1936 saw unusual heat build initially in two nodes, one centered over the Southeast and another over the Rocky Mountains and western Plains. By the end of June 1936, all-time state monthly records for heat had been established in Arkansas (113°F at Corning on June 20), Indiana (111°F at Seymore on June 29), Kentucky (110°F at St. John on June 29), Louisiana (110°F at Dodson on June 20th), Mississippi (111°F at Greenwood on June 20), Missouri (112°F at Doniphan on June 20), Nebraska (114°F at Franklin on June 26), and Tennessee (110°F at Etowah on June 29).

Then the heat really cranked up. By July, the dome of heat was locked in place over the central and northern Great Plains, and it remained there for the entire month.

Around July 8-10, the extreme heat briefly extended all the way to the East Coast when virtually every absolute maximum temperature record was broken from Virginia to New York. This held true for most sites in the Ohio Valley, Upper Midwest, and Great Plains as well. There are so many superlatives that it is impossible to list them all. In short, the following states broke or tied their all-time maximum temperatures that July

Some of the many major U.S. cities to record their all-time maximum temperatures during July 1936 (many of these records still stand) included:

On July 15, the average high temperature for all the official weather sites in Iowa measured 108.7°F. Nighttime low temperatures were also remarkably warm. Bismarck recorded a low of just 83°F on July 11. Milwaukee, Wisconsin, endured five consecutive nights above 80°F from July 8 to 13. Even near the normally cool shores of Lake Erie, amazing temperatures were observed, such as the low of 85°F and high of 110°F at Corry, Pennsylvania, on July 14. Most amazing of all was the low of 91°F at Lincoln, Nebraska, on the night of July 24-25, warming to an all-time record high of 115°F on the 25th.

By August the heat dome shifted a bit further south from its position over the northern Plains and became anchored over the southern Plains.

All in all, nothing comparable to the heat wave(s) of the summer of 1936 has before or since occurred in the contiguous U.S. It is hard to imagine how people fared without home air conditioning, although there were some rudimentary forms available, such as swamp coolers. Movie theaters were one of the few places where air conditioning provided at least some temporary relief.

Many people have wondered just why the temperatures reached such anomalous heights that summer. There was no La Niña event (which often results in summer heat waves in the U.S.), according to historical analysis of such. The Pacific Decadal Oscillation was in a strongly positive mode, according to NOAA.

One widely accepted theory is that the Dust Bowl drought (which was in its third year by 1936), combined with unsustainable land-use practices in the preceding years, degraded ground cover to such a degree in the Plains and Midwest that the air became unusually dry and super-heated, thus facilitating extremely high temperatures. This would mean that, given improved agricultural practices, such temperatures are not likely to occur again anytime soon (at least on such a broad scale). Of course, climate change will make that assumption less likely sooner or later.

The impact of the 1930s drought and Dust Bowl on the extreme temperatures was analyzed by earth scientists Benjamin Cook and Richard Seager in a 2009 paper published by the National Academy of Sciences. The authors found that climate models that included the sea surface temperatures prevailing at the time were able to replicate the 1930s drought. However, the models incorrectly placed the center of the drought across the southwest U.S., and they did not replicate the extreme heat over the Central and Northern Plains. The models did much better at reproducing the fingerprint of 1930s heat when they included the lack of vegetation and the widespread blowing dust prevalent over the Great Plains.

However, this can only explain one facet of the 1936 heat event, since all-time record maximum temperatures were also observed from Idaho in the west to New York and New Jersey in the east, far from the area impacted by the drought. It would be useful to run a reanalysis of the meteorological elements in play during that torrid summer in the hopes of unlocking the full story behind this event and determining what the odds of a repeat might be. It has been six years since the last major summer-long heat event (summer of 2012) affected the Midwest and the eastern half of the U.S.

Christopher C. Burt-Weather Historian

So even though we have some toasty weather ahead, it will pale when compared to July of 1936. We can be thankful for that. Here's the general upper air pattern that causes our temperatures to rise in coming days.

The next 10 days of highs as shown by the EURO here in Cedar Rapids.

If we get 8 consecutive days in the 90s that will be the first time since 2012 that's happened. If we can pull off 9 days, that would be the longest stretch of 90s since 1995 (24 years)!

Dew points will also be on the increase which means it will turn steamy and the heat index will become a factor to monitor..

By Sunday, the heat index in some parts of my area should approach 100 degrees. The actual high 92.

While some parts of the north may see some scattered storms Friday night and Saturday, most of the rain that falls in the next 6-10 days looks to focus on Minnesota and Wisconsin, maybe far northern Iowa. No doubt about it, summer has finally found us. Roll weather...TS

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