July 18, 2020

July's Memorable Heat Wave Will Continue With Dangerous Heat in Midwest, Mid-Atlantic

The relentless heat and humidity that's bathed the United States since the end of last month will keep going straight through next week as temperatures push the triple-digit mark in the nation's capital. The above-normal sultriness looks like it'll continue into August if the latest monthly outlooks come to pass.

Heat advisories and excessive heat warnings are in effect across much of the Plains and Midwest on Saturday as the heat and humidity reaches its apex across the region. The heat index could reach 105-110°F as far north as Minneapolis on Saturday afternoon, potentially leading to heat-related injuries and illnesses in a hurry without proper protection.

The heat will shift east between Sunday and Tuesday, pushing high temperatures close to 100°F in the Mid-Atlantic and parts of the Northeast.

Here's the National Weather Service's forecast high temperatures between Saturday and Tuesday:





The latest uptick in temperatures is hardly a welcome change right now. If you live in one of the comfortable corners of the country where you haven't broken a sweat just looking out the window, you don't realize just how hot it's been this month.

The temperature reached 121°F in Palm Springs, California, on July 12, tying the second-hottest temperature on record there. The temperature in Phoenix rose above 90°F on July 8 and didn't fall below 90°F until the morning of July 15°F, hitting triple digits each afternoon in between, maxing out at 116°F on July 12.

A humid heat plagued the southern Plains for much of last week. The dew point reached 80°F in Norman, Oklahoma, for the first time since the Oklahoma Mesonet began taking readings there—such a deep slog of moisture is disgusting even by tropical standards, let alone on the Plains. 

Temperatures were relentlessly gross back east. Washington D.C. came close to breaking its longest recorded streak of high temperatures at or above 90°F. National Airport recorded a high of ≥90°F for 20 straight days between June 26 and July 16, falling one day short of tying the record set in August 1980 and August 1988.

The Climate Prediction Center's latest outlook says all indications point toward abnormally warm temperatures to continue through the end of the month, especially across the northern half of the country. Not only is this kind of pattern brutal on people and groups sensitive to relentless heat and humidity—folks who are sick, the elderly, low-income folks who can't afford air conditioning or fans—but it's ripe for severe thunderstorms, which can add insult to injury during a nasty spell of heat.

Persistent heat can lead to severe weather like we're seeing in the Upper Midwest tonight. Ridges of high pressure that lead to these prolonged heat waves can foster severe squall lines that produce intense wind gusts, leaving behind widespread wind damage over a path that can stretch hundreds of miles long.

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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I contribute to The Weather Network as a digital writer, and I've written for Forbes, the Washington Post's Capital Weather Gang, Popular Science, Mental Floss, and Gawker's The Vane. My latest book, The Skies Above, is now available. My first book, The Extreme Weather Survival Manual, arrived in October 2015.