Extreme heat in Southwest could send temps toward 120 in Phoenix
Temperatures already well into the triple digits across the Southwest are forecast to rise even higher as a heat dome intensifies over the region. An excessive heat warning is in effect for the Phoenix area.
Heat will intensify further across the Southwest as cooler air returns to the coastal Northwest.
A new surge of heat in the southwestern United States will push temperatures to higher levels than experienced so far this summer and perhaps within a few degrees of all-time record levels in some locations. The extreme heat will pose dangers even for long-term residents who are used to extremely hot summers. And as the brush continues to dry out in the sweltering heat, the risk of wildfires will grow.
AccuWeather meteorologists are particularly concerned about the intensity and duration of the heat in the coming days and weeks. They also note that temperatures will remain quite high during the nighttime hours.
The southwestern U.S. is routinely a hot place in the summertime, but the upcoming heat in store for the middle of July will be extreme. Conditions may become life-threatening.
A saguaro cactus stands against the rising sun Monday, Feb. 22, 2016, in the desert north of Phoenix. (AP Photo/Charlie Riedel)
For example, the combination of dry air and heat may cause many individuals to become dehydrated and perspiration may dry too quickly to take notice.
Experts urge people to remain hydrated, avoid physically strenuous activities and seek air-conditioned environments when and where possible.
"A dome of high pressure and heat will build over the southwestern U.S. this week after a brief roll-back with high temperatures this weekend," AccuWeather Senior Meteorologist Heather Zehr said. "The jet stream and high pressure area will shuffle around through this weekend but will align in such a way as to give temperatures a significant boost in the region this week."
AccuWeather forecasters have been combing meteorological data and have reason to believe that temperatures will exceed previous high marks observed at the start of July for several days later this week. This includes the potential for Phoenix to come close to a rarely observed temperature in the region.
Phoenix has only reached the 120-degree-Fahrenheit mark three times since records have been kept dating back to 1929. The last time temperatures topped that mark was on July 28, 1995, when a high of 121 was recorded. The all-time record high of 122 was set on June 26, 1990.
Phoenix is highly likely to reach the upper 110s for multiple days this week and could sneak to or just past the 120-degree mark provided no thunderstorms erupt to cool and moisten the local environment. When a downpour occurs, some of the sun's energy is used up evaporating moisture instead of heating the ground and the air.
Currently Thursday appears to be most likely to break the 120 degree threshold in Phoenix. A high of 119 F is forecast for the city, which would break the current record for the date of 114 F that was set in 2020.
Additionally, temperatures will remain at abnormally warm levels overnight. While temperatures typically fall to the low or mid 80s overnight, they may remain in the low 90s across most of the Phoenix metro area for several nights this week.
An excessive heat warning has been issued for the Phoenix area, and it will remain in effect through July 16, according to the National Weather Service. Other watches and advisories related to heat have been hoisted across southeastern California and southwestern Arizona, as well as southern New Mexico and southwestern Texas.
There is the potential for Phoenix to set a record, in addition to some daily highs, even if the all-time record is not matched or bettered, AccuWeather director of forecast operations Dan DePodwin said.
"Phoenix has hit 110 degrees or higher each day since June 30 and has a chance at breaking the 18-day record for that temperature mark with this stretch," DePodwin said. That record was set way back in 1974.
Will the North American monsoon develop soon?
The position of the high pressure area and the core of the jet stream bulge will set up in such a way as to limit the amount of moisture that can sneak in from the Pacific and Gulf of Mexico. This moisture surge that is associated with a change in the wind direction is called the North American monsoon.
"Thunderstorm activity is likely to be very sparse over much of the southwest U.S. through the week," Zehr said. "That sparse activity will probably be limited to the mountains and may only contain very brief, isolated downpours."
It is possible that some recycled moisture from thunderstorms well to the north over the Rockies and to the east over the Great Plains could infiltrate the Southwest at some point over the next week without the true change in winds.
"There are some signs that the monsoon may develop in the latter part of July, but the northward expansion of moisture may still be below average in terms of coverage and intensity across the Four Corners region," AccuWeather Long-Range Meteorologist Brandon Buckingham said.
A number of locations from the interior valleys and deserts of California through much of the Great Basin that encompasses Nevada, Utah, Arizona and western Colorado, as well as the mountains and valleys of New Mexico to the High Plains of West Texas are likely to reach season-high marks and potentially could come within a few degrees of their all-time record highs throughout this week and into the end of July.
Temperatures in many cities could approach all-time highs
During the second week of July, temperatures will challenge all-time record high levels for many locations over the interior Southwest.
Las Vegas has hit its all-time record high of 117 five times over the years, with the most recent occurrence being on July 10, 2021. Temperatures are likely to reach the mid-110s on multiple days this week and potentially could add another day to the all-time list. So far this summer, Sin City has maxed out at 112 on July 3 but did not have its first triple-digit temperature of the summer until June 30, which set a record for consecutive days in which high temperatures remained 100.
Salt Lake City is another location that will experience multiple days with highs of 100 or greater thanks to the searing heat on the way. Utah's capital city hit 101 on July 3, which was its high mark for the year so far. However, temperatures may top this mark on one or more occasions from Sunday to Wednesday. The all-time record high for Salt Lake City of 107 was set on July 17, 2022.
Palm Springs, California, has had temperatures in the low 120s multiple times over the years, with the all-time high of 125 set on July 28, 1995. The desert city did not hit the 120-degree mark last year but did so each month in June, July and August of 2021. On Thursday, a high of 119 F is forecast for the city.
The world record air temperature of 134 in Death Valley, California, set on July 10, 1913, will almost certainly remain intact. However, temperatures are likely to surge into the 120s on multiple days this week. Earlier this week, a man was found dead in his vehicle in Death Valley National Park. Officials believe extreme heat played a role in the man's death.
If or when some moisture is able to make it into the Southwest, higher humidity levels may begin the cycle of spotty thunderstorm activity and a slight cooldown.
However, the first thunderstorms, whether that is the week coming up or later this summer, could be mainly dry and accompanied by lightning strikes capable of igniting wildfires. In the meantime, meteorologists say caution should be used with regard to open flames, outdoor power equipment and vehicle exhaust systems, as sparks or extra heat could ignite the dry brush.
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