News•June 28, 2012

Massive 'Debilitating' Heat Wave Expands Eastward

An historic heat wave that has helped create tinderbox conditions in Colorado and other Western states is moving east, with record-breaking temperatures expected in at least 13 states Thursday, from Oklahoma to Ohio. Already during the past seven days, 1,701 warm temperature records had been tied or set across the U.S., compared to 401 cool temperature records during the same period.

The maximum heat index forecast for June 30. Click on the image to see a larger version. Credit: NWS.

As occurred during the March 2012 heat wave, some of the records that have fallen eclipsed readings not seen since the Dust Bowl-era of the 1930s. The National Weather Service is describing the heat as “debilitating,” warning millions of Americans affected to take precautions against heat-related illness.

The heat in the West has helped fuel the devastating wildfires in Colorado, where the Waldo Canyon Fire burned hundreds of homes in Colorado Springs on Tuesday and Wednesday. Now that the heat is moving east, it is prompting concerns about the U.S. corn crop, which is particularly sensitive to dry and hot conditions at this time of year.

Benkelman, Neb., set a monthly high temperature record on Wednesday, when the temperature hit 114°F, breaking the old mark of 111°F set in 1936. Dodge City, Kan., set an all-time high temperature record of 111°F, beating the previous mark of 110°, which was set just a day before. (Track record temperatures using Climate Central's Record Tracker.) As The Weather Channel noted, at least 10 cities in the Rockies and High Plains had high temperatures that were hotter than Death Valley, Calif. on June 26.

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During the June 21-27 period, 199 monthly high temperature records were set or tied, along with 49 monthly warm overnight low temperature records. This compares to just one monthly cold high temperature record, and one monthly cold overnight low temperature record during the same period.

For the year-to-date, warm temperature records have been outpacing cold temperature records by about 7-to-1.

In a long-term trend that demonstrates the effects of a warming climate, daily record-high temperatures have recently been outpacing daily record-lows by an average of 2-to-1, and this imbalance is expected to grow as the climate continues to warm. According to a 2009 study, if the climate were not warming, this ratio would be expected to be even. Other studies have shown that climate change increases the odds of extreme heat events and may make them warmer and longer lasting.

Triple-digit heat is forecast to move east by the weekend, with 100-degree-plus days likely in the Mid-Atlantic, South Central, and Southeast. Heat indices, which measures how hot it feels to the human body, are forecast to climb as high as 115°F or greater in some locations, prompting the issuance of heat watches and warnings. Overnight low temperatures will fail to provide much relief, as temperatures are forecast to remain above 80°F. Public health studies have shown that overnight low temperatures help make heat waves more deadly for people who lack air conditioning by preventing them from cooling down. The public health threat from this heat wave may also be exacerbated by the fact that it is taking place early in the summer season, before many people have become accustomed to very warm weather.