100 million to swelter daily in massive US heat dome
A massive heat dome will be long-lasting and unforgiving across large areas of the United States in the coming weeks, with AccuWeather RealFeel® Temperatures occasionally surpassing 110 F.
In the middle of a heat wave, you may come across what appears to be water boiling on a hot road. AccuWeather’s Ali Reid explains the science behind this shimmering illusion.
A large, late-July heat dome will shift back and forth across a large part of the United States through the end of the month, with 100 million people or more to endure 100 F AccuWeather RealFeel® Temperatures on a daily basis.
While late July often brings the highest temperatures of the year for much of the U.S., a heat wave combined with intense sunshine and high humidity can be brutal for those who do not have air conditioning or a means to cool off by way of a refreshing pool, lake or beach.
Despite being a traditionally hot time of the year, temperatures will run 5-15 degrees Fahrenheit above the historical average, with highs of 95 or higher.
"While this is not really a record-breaking air mass in terms of high temperatures, some towns and cities will struggle to drop below 80 degrees at night due to the high humidity levels and retention of heat by vast areas of concrete and pavement," AccuWeather Senior Meteorologist Brett Anderson said. "For those that only have a fan or open window to keep cool, sleeping will be difficult for some, with a high risk of dehydration."
One particular zone will experience the worst of the conditions on a daily basis as the heat dome builds eastward, then shuffles westward in the coming days.
During the days, temperatures will reach 100 degrees from Texas to western Tennessee just about every day for the next one to two weeks. Many of these locations were behind schedule, not in terms of days with 100-degree heat, but some had not yet reached 100 this summer prior to this week. Through Monday, July 21, Oklahoma City; Little Rock, Arkansas; Wichita, Kansas; Dallas; and Shreveport, Louisiana; all had yet to hit triple digits so far this year.
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While a zone of strong high pressure and a northward bulge in the jet stream will be the main sources of sunshine and heat, the Gulf and Atlantic will be the primary sources of high humidity levels in the region. In the Central states, where vast fields of maturing crops are present, the evaporation of moisture from the corn stalks (corn sweat) will help boost humidity levels as well.
"The combination of extreme temperatures, high humidity and light winds will likely send afternoon AccuWeather RealFeel® Temperatures to between 110 and 115 F from the states that touch the western part of the Gulf through Oklahoma and Arkansas, as well as portions of Missouri, Illinois, Indiana and Tennessee," Anderson said. "At this level, it can be dangerous for many people who are exposed to the heat for an extended period of time, leading to heat-related illnesses that can sneak up on some individuals."
Friends, neighbors, family members, and work colleagues are encouraged to check on those who may be in heat distress, especially young children, senior citizens, and those who toil in manual labor.
The dome of heat will stretch eastward later this week and bulge into the Northeast.
From later this weekend to early next week, the main dome of heat will shift into the Southeast states, as well as expand and strengthen over the Central states. Late in July to early August, the heat dome may expand to include much of the interior West as much cooler and less humid air slices southward over the Midwest and Northeast.
In the core of the heat dome, few, if any, thunderstorms will occur. However, thunderstorms will be quite active on the edges. Where storms do occur, they can be especially nasty, with heat on one flank and slightly cooler air on the other providing extra energy. Enough moisture will be present to raise the risk of flash flooding in the stormy zones.
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