Comment More than 100 million people in the Lower 48 states are under a heat alert Thursday amid unrelenting temperatures that have soared as high as 115 degrees in recent days. About 60 million Americans in at least 16 states are set to experience triple-digit highs Thursday. another half dozen states could see the mercury reach the upper 90s. Extreme heat warnings or heat advisories cover many areas, including California’s Central Valley. Las Vegas to Phoenix in the Southwest. San Antonio to Birmingham, Ala., in the South. and Myrtle Beach, SC, to Boston along the East Coast. In Texas and Oklahoma, where many places are enduring one of the hottest summers on record, high temperatures well over 100 degrees are expected in the near future. Both states reached 115 degrees on Tuesday, and while temperatures are comparatively cooler on Thursday, they will still be dangerous for vulnerable groups. Major cities in the Northeast will see highs near 95 degrees Thursday and feel 5 to 10 degrees warmer with sweltering 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. The US heat wave, which has set at least 60 records, peaked this week as a historic spell of extreme temperatures killed more than 1,000 people in Europe. Britain set a record temperature on Tuesday as several stations topped 40 degrees Celsius (104 degrees Fahrenheit) for the first time. Britain’s blistering heat has broken records. Here’s what happened. While the summer is expected to be hot, the trend towards increasingly severe and long-lasting heat waves bears the fingerprint of human-induced climate change. So far this week, 60 daily high temperature records have been set/broken as dangerous heat enveloped much of the Nation. Some notable records include all-time highs in Salt Lake City, UT and Abilene, TX. More records are likely to be set next week. pic.twitter.com/uI1JeHIwcW — NWS Weather Prediction Center (@NWSWPC) July 21, 2022 The nation’s hottest heat Thursday is centered in the Southwest. The National Weather Service warned of a “high risk of heat-related illness” in Las Vegas, where highs are expected to reach 110 degrees by Friday. ⚠️ The next few days will be warm for Las Vegas, but 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 National Weather Service also warned of “dangerous temperatures” in Phoenix, where highs are expected to reach 110 to 115 degrees. The city is also under a pollution alert due to high levels of harmful ground-level ozone. Highs could top 120 degrees in Death Valley, Calif., by Saturday. Heat waves are getting hotter and more frequent. Here’s how to prepare.
Hot 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, every one of the Oklahoma Mesonet’s 120 weather stations recorded a high temperature of 103 degrees or above for the first time. Mesonet has been in operation since the mid-1990s, which means that the recording period is limited. Regardless, the heat was blistering. At least 24 Mesonet sites hit all-time highs yesterday according to preliminary data. There are a few newer stations in there, but plenty to show that this day matches in heat with anyone in the Mesonet 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 and has reached the century mark for five straight days. When it reached 110 on Tuesday, it was only the second such occurrence since 2012. High temperatures there are forecast to remain in the high 90s or low 100s for at least the next week. Mangum, Okla., jumped to 115 on Tuesday, as did Wichita Falls, Texas. While temperatures were cool, those temperatures still shy of the 120-degree mark at Altus in southwest Oklahoma on August 12, 1936. That’s the all-time state record. About a dozen small fires have been burning in Oklahoma’s Red River Valley and north-central Texas, the largest of which is in Somervell County 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. Only 10 percent is contained. The calculation was attempted showing a departure from the average number of hours with a heat index of at least 100°F so far this year. All heat index references (i.e. when less than air temperature) are taken into account. X’s denote stations with peak values this year compared to 1973-2021. pic.twitter.com/SlFabOUm31 — Daryl Herzmann (@akrherz) July 21, 2022 Dallas, Austin, San Antonio and Tulsa will remain at or above 100 degrees for at least the next week, while areas further south and east – Houston, Little Rock or Shreveport, La. – will be in the 90s. These slightly cooler air temperatures will be offset by more moisture coming in from the Gulf of Mexico, contributing to heat index values in the 105 to 110 degree range. Much of the belt from Louisiana and Arkansas to Georgia is experiencing one of the 10 hottest summers, and temperatures will remain high into early next week. Highs are forecast to range from 90 to 100, but oppressive humidity levels will make it feel like 100 to 110. We have an extreme heat warning in effect for our western counties until 7pm tonight as heat index values will reach near 110 degrees. Heat Advisory in effect for all but far eastern counties until 7pm tonight where heat index values will range from 105-108 degrees. pic.twitter.com/AXiP6KCOZq — NWS Birmingham (@NWSBirmingham) July 21, 2022 Birmingham, Ala., is under a heat advisory Thursday, with temperatures expected to top out around 95 degrees. West Alabama may see highs in the upper 90s. While the daytime highs weren’t particularly impressive there from a record, the overnight lows were. “We had a low of 79 degrees yesterday [Wednesday] morning,” said Jason Holmes, a meteorologist at the Weather Service’s Birmingham office. “Having nighttime cold temperatures like that — it’s hard on your body because you’re not getting cold.” What does excessive heat do to the human body?
Warm 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 changing quickly. Temperatures are expected to reach the 90s from Richmond to Boston on Thursday, with heat index values in the triple digits. While the humidity will ease a bit on Friday behind a weak cold front, the oppressive gloom returns for the weekend. Highs in New York will flirt with 90 degrees through Saturday, then jump into the mid to upper 90s on Sunday. Washington, Baltimore and Philadelphia will be in the mid-90s through Saturday, approaching 100 degrees on Sunday. Heat index values could reach 105 to 110.
What drives the heat Driving the heat is a ridge of high pressure known as a “heat dome,” which is centered in the Southwest but bends at times as far east as the Mid-Atlantic. Beneath these domes of heat, air sinks, clearing the clouds while letting the sun beat down relentlessly. At the top of the heat dome is the jet stream, which marks the southern periphery of colder weather. The science of heat domes and how drought and climate change are making them worse Over the weekend, the jet stream will make a dive toward the north central United States and the Great Lakes, bringing cooler air into those areas. However, as cooler air arrives, strong to severe thunderstorms may develop on Saturday.
