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More than 100 million people in the Lower 48 states are under heat warnings Thursday amid unrelentingly hot temperatures that have soared to 115 degrees in recent days.
About 60 million Americans in at least 16 states will experience triple-digit highs Thursday; another half-dozen states could see the mercury reach the upper 90s.
Excessive heat warnings or heat advisories cover several regions, including California’s Central Valley; Las Vegas to Phoenix in the southwest; San Antonio to Birmingham, Alabama, in the south; and Myrtle Beach, South Carolina, to Boston on the East Coast.
In Texas and Oklahoma, where many places are experiencing one of the hottest summers on record, high temperatures well over 100 degrees are expected for the foreseeable future. Both states reached 115 degrees on Tuesday, and although temperatures are relatively cooler on Thursday, they will still be dangerous for vulnerable groups.
Major cities in the Northeast will experience high temperatures near 95 degrees Thursday and feel 5 to 10 degrees hotter with stifling humidity levels. Even more intense heat is forecast this weekend: Washington could hit 100 for the first time since 2016.
D.C. Mayor Muriel E. Bowser declared a heat emergency for the city until Monday.
A US heat wave that has set at least 60 records reached its peak this week as a historic spell of extreme temperatures killed more than 1,000 people in Europe. Britain set a record high temperature on Tuesday as several stations topped 40 degrees Celsius (104 degrees Fahrenheit) for the first time.
Great heat in Britain has broken records. Here’s what happened.
While summers are bound to be hot, the trend toward increasingly severe and prolonged heat bears the imprint of human-induced climate change.
So far this week, 60 daily high temperature records have been tied/broken as dangerous heat enveloped much of the nation. Some notable records include all-time highs in Salt Lake City, Utah and Abilene, Texas. More records are likely to be set in the coming week. pic.twitter.com/uI1JeHIwcW
— NWS Weather Prediction Center (@NWSWPC) July 21, 2022
The most intense heat in the country on Thursday is concentrated in the southwest. The National Weather Service warned of a “high risk of heat-related illness” in Las Vegas, where temperatures are expected to reach 110 degrees through Friday.
⚠️ The next few days will be hot for Las Vegas, but also for much of southern Nevada and northwestern Arizona.
Take extra precautions to avoid heat illness! 🥵️ pic.twitter.com/rvMgHaSxqY
— NWS Las Vegas (@NWSVegas) July 21, 2022
The weather service also warned of “dangerously hot conditions” in Phoenix, where high temperatures are expected to reach 110 to 115 degrees. The city is also under a pollution warning due to high levels of harmful ground-level ozone.
Highs could reach 120 degrees in Death Valley, California by Saturday.
Heat waves are getting hotter and more frequent. Here’s how it’s prepared.
Heat in Texas and Oklahoma
The heat in Texas and the Southern Plains has been unforgiving this summer, with San Antonio, Austin and Houston enduring their hottest temperatures on record. There is little sign of relief.
On Tuesday, each of Oklahoma Mesonet’s 120 weather stations recorded a high temperature of 103 degrees or above for the first time. The maisonette has been operating since the mid-1990s, which means the recording period is limited. Regardless, the heat was incredible.
At least 24 Mesonet sites set all-time highs yesterday, according to preliminary data. There are a few newer stations out there, but plenty to show this day matches in terms of heat all in the Maisonette temperature era dating back to 1997! #okwx #okmesonet pic.twitter.com/uVSPIyqYVx
— Oklahoma Mesonet (@okmesonet) July 20, 2022
Oklahoma City soared to 100 degrees Wednesday, making it the century mark for five straight days. When it hit 110 on Tuesday, it was just the second such high since 2012. Highs there are forecast to stay around 90 or 100 degrees for at least the next week.
Mangum, Okla., jumped to 115 on Tuesday, as did Wichita Falls, Texas. Although sweltering, those temperatures were still lower than the 120-degree reading at Altus in southwest Oklahoma on August 12, 1936. That’s the all-time record.
About a dozen small wildfires have broken out in Oklahoma’s Red River Valley and north-central Texas, the largest of which is in Somervell County, just southwest of the Dallas-Fort Worth metroplex. The Chalk Mountain Fire has burned 6,339 acres since it ignited around 2:30 p.m. Monday. It contains only 10 percent.
Attempted calculation showing deviation from average number of hours with at least 100°F heat index so far this year. All heat index reports are taken into account (ie when it is lower than the air temperature). X stands for stations with maximum values this year vs. 1973-2021 pic.twitter.com/SlFabOUm31
— Daryl Herzman (@akrherz) July 21, 2022
Dallas, Austin, San Antonio and Tulsa will stay at or above 100 degrees for at least the next week, while areas farther south and east — Houston, Little Rock or Shreveport, La. — will be in the upper 90s. These slightly cooler air temperatures will be offset by higher humidity moving in from the Gulf of Mexico, contributing to heat index values in the 105 to 110 degree range.
Much of the area from Louisiana and Arkansas to Georgia is experiencing one of its 10 hottest summers, and temperatures there will remain hot into early next week. Highs are expected to range from 90 to 100, but oppressive humidity levels will make it feel like 100 to 110.
We have an excessive heat warning in effect for our western counties until 7pm tonight as heat index values will reach near 110 degrees. A heat advisory is in effect for all counties in the Far East until 7:00 PM tonight, where heat index values will range from 105-108 degrees. pic.twitter.com/AXiP6KCOZq
— NWS Birmingham (@NWSBirmingham) July 21, 2022
Birmingham, Alabama, is under a heat advisory Thursday, with temperatures expected to top out around 95 degrees. West Alabama could see highs in the upper 90s. While the daytime highs weren’t particularly impressive in terms of records, the overnight lows were.
“Yesterday we had a low temperature of 79 degrees [Wednesday] morning,” said Jason Holmes, a meteorologist at the Met Office’s Birmingham office. “With the cold temperatures at night, it’s hard on your body because you’re not cooling down.”
What causes excessive heat to the human body?
Warmth in the Mid-Atlantic and Northeast
Hot and humid conditions are expected today. Scattered showers and thunderstorms will develop this afternoon, mainly south of Washington, DC. A strong to severe storm with damaging winds is possible. pic.twitter.com/XSmE4p1YZA
— NWS Baltimore-Washington (@NWS_BaltWash) July 21, 2022
The Mid-Atlantic and Northeast were largely spared the heat and humidity this summer, but that is quickly changing.
Temperatures are forecast to reach the 90s from Richmond to Boston on Thursday, with heat index values in the triple digits.
While the humidity will drop somewhat on Friday behind a weak cold front, the oppressive stuffiness returns over the weekend.
Highs in New York will flirt with 90 degrees through Saturday, then jump into the mid or upper 90s on Sunday. Washington, Baltimore and Philadelphia will be in the mid to upper 90s through Saturday, approaching 100 degrees on Sunday. Heat index values can reach from 105 to 110.
What causes the heat?
The heat is driven by a ridge of high pressure known as a “heat dome” that is centered over the southwest but sometimes bends eastward into the Mid-Atlantic.
Below these heat domes, the air sinks, clearing the cloud cover while allowing the sun to burn relentlessly. At the top of the heat dome is the jet stream, marking the southern edge of cooler weather.
The science of heat domes and how drought and climate change are making them worse
Over the weekend, the jet stream will dip toward the north-central United States and the Great Lakes, bringing cooler air into those areas. However, with the arrival of this cooler air, strong to severe thunderstorms may develop on Saturday.
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