Tucson, Phoenix and Mesa in Arizona are among the hottest cities in the Lower 48 states,
Where records could occur
Numerous records for high temperatures and streaks of hot weather could be set over the next two weeks.
Phoenix has hit at least 110 degrees seven days in a row
Extreme heat wave bound for Phoenix and Southwest could be worst ever
The Southwest United States is about to endure a heat wave that could rank among its worst in history — both for its intensity and longevity.
The heat wave will affect much of Arizona and New Mexico and build into interior California, probably peaking during the second half of next week. The National Weather Service office in Phoenix says it will “rival some of the worst heat waves this area has ever seen.”
While it’s already excessively hot in the region, it will get significantly worse next week, and it’s unclear when the heat will ease. Computer models that project the weather 16 days into the future “do not show an end to this heat wave,” the Weather Service wrote in a discussion. “This should go down as one of the longest, if not the longest duration heat wave.”
While summer started off tame in the region (Las Vegas didn’t hit 100 until June 30, ending a record streak of not hitting the century mark), the heat began to ramp up quickly in recent days. In Phoenix, it was 115 degrees on Thursday, following 116 on the Fourth of July. The temperature in Death Valley, Calif., soared as high as 126 in the past week.
An excessive heat warning is in place through at least July 13 for much of south-central Arizona, including Phoenix and Tucson. In addition to a week or more of days with extreme heat, temperatures won’t drop too far at night, offering little relief and posing a health risk for those without access to air conditioning.
“Very dangerous to potentially life-threatening heat conditions are expected through next week and it is very essential that all the necessary heat precautions be taken to avoid any heat-related illnesses,” the Weather Service wrote.
In Phoenix, every day for the foreseeable future should reach at least 110 degrees.
The worst of the heat will probably occur during the second half of next week in Phoenix.
“From next Tuesday through the rest of the week, temperatures across the region may be some of the hottest we have ever seen,” the Weather Service wrote.
Related video: Triple-digit temperatures remain in forecast for part of the Southwest (AccuWeather)
AccuWeather
Dailymotion
ABC15 Phoenix, AZ
TODAYPhoenix has witnessed three days in history of 120 degrees or higher, with its hottest day coming in June 1990 when it hit 122 degrees. The forecast there goes as high as 117 degrees Wednesday, but the Weather Service cautioned that computer models show the possibility of 120-degree temperatures in the area.
To the north, “temperatures in Las Vegas may reach 110 degrees by the middle of the week, and 120 degrees in Death Valley,” wrote the Weather Service office in Las Vegas. And it could get hotter after that.
Temperatures of 110 to 120 degrees are also slated to be common across Southern California’s deserts into next week, along with 100 to 105 in the Central Valley. Similar levels of debilitating heat are forecast to extend eastward across the southern half of New Mexico and into adjacent parts of northern Mexico.
In the very high terrain of the Sierra Nevada, the hot weather is melting the remnants of a record-setting winter snowpack, triggering localized flooding that is expected to continue.
The heat in the region is being intensified by a delayed start to monsoon season, which runs from June 15 to Sept. 30 on average. Often, monsoons draw moisture and bring clouds and storms into the Southwest, putting a cap on temperatures by mid-July.
Where records could occur
Numerous records for high temperatures and streaks of hot weather could be set over the next two weeks.
Phoenix has hit at least 110 degrees seven days in a row and could approach the record of 18 days set in June 1974.
Other numbers to watch include:
- Tucson may test calendar day record highs almost daily over the coming period, nearing 110 degrees by the middle of next week.
- Phoenix could challenge its calendar day record high Wednesday. Its high is forecast to be 117. The record of 116 degrees was set in 2020. Overnight lows near and above 90 degrees may also set records for warmest nights, especially next week.
- Death Valley is forecast to breach 120 degrees by Wednesday and head higher after that. It hit 126 degrees on July 2.
- Imperial, Calif., near the Mexico border, is forecast to reach 117 degrees by Wednesday, potentially beginning a streak of daily records there.
Records may become much more numerous by the second half of next week, when the heat is expected to peak in coverage and intensity. Record-challenging heat could threaten a sprawling region from near Los Angeles to Albuquerque by July 13.
How long
There’s no clear end in sight to this heat wave. The heat dome, set to expand and strengthen over the region, may persist beyond the limits of current forecasts.
How long this heat wave lasts may ultimately depend on whether monsoon season kicks in, but forecasters expect a near- to below-average monsoon season after a very active one last year.
The hottest time of year in Arizona is often late June into early July, highlighted in the graph below of cumulative days at or above 105 degrees in Phoenix. Deeper into July, and more noticeably by August, clouds and rain generated by monsoons tend to reduce the heat but increase humidity.
Because of monsoon season, Phoenix typically has seen its hottest weather by mid-July. Of the 19 days on record with highs of at least 118 degrees, only four came after that. The caveat, of course, is that historical norms don’t necessarily apply in our rapidly warming climate.
Jason Samenow contributed to this report.
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