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Extreme Heat Warnings issued, temperatures up to 49°C (120°F) forecast across western U.S.

ByRishav Kothari

Friday, July 31, 2026 10:02 UTC

A dangerous heatwave is forecast to intensify across the southwestern United States on Friday, July 31, 2026, and then spread into the Intermountain West and northern High Plains during the weekend, according to the Weather Prediction Center (WPC).

Image credit: NWS/WPC

Dangerous heat is forecast to peak across the Southwest before expanding into Nevada, Wyoming, Montana and other parts of the Intermountain West and northern High Plains through the weekend.

Temperatures in parts of the Southwest could reach 43–49°C (110–120°F), while warm nights will provide little relief in several areas.

The Weather Prediction Center’s Western U.S. Heat Wave key message, updated on July 30, forecasts widespread Major to Extreme HeatRisk. While dozens of daily high-temperature records and several monthly records could be broken, some locations could experience one of their ten hottest days on record.

Farther north, temperatures of about 32–43°C (90–109°F) are forecast across parts of the Intermountain West and northern High Plains.

Image credit: NWS/WPC

Extreme Heat Warnings were still active across large parts of the Southwest at 08:37 UTC on July 31. The National Weather Service office in Phoenix forecast afternoon temperatures of 44–47°C (112–117°F) in the Phoenix metropolitan area through 20:00 MST on August 3 (03:00 UTC on August 4).

Temperatures of 44–49°C (112–120°F) are forecast for Yuma, the Imperial Valley, Parker Valley and Palo Verde Valley. Mostly rural areas of southwestern Arizona and southeastern California could reach 42–49°C (108–120°F).

Warnings in Southern California cover inland valleys, coastal mountain ranges, foothills and desert areas. The National Weather Service office in Los Angeles/Oxnard forecast temperatures of 35–43°C (95–110°F) across a large part of southwestern California from 10:00 PDT (17:00 UTC) on July 31 through 20:00 PDT on August 2 (03:00 UTC on August 3).

The Antelope Valley could reach 41–46°C (105–115°F). The weather office said dangerous heat could continue into the following week in parts of the region.

Extreme heat is also affecting lower-elevation areas of northern Arizona. The National Weather Service office in Flagstaff forecast daytime temperatures of 44–47°C (112–117°F) at Phantom Ranch and 40–43°C (104–109°F) at Havasupai Gardens through Sunday evening.

The warning states that most people without effective cooling or enough water could develop heat-related illness, especially during long periods outdoors.

Heat alerts also extend north through Nevada, Wyoming and Montana. Mineral and southern Lyon counties and the western Nevada Basin and Range could reach 38–41°C (101–105°F). Overnight temperatures there are forecast to remain at 18–21°C (65–70°F) through Sunday morning.

A Heat Advisory covers much of western and central Wyoming on Saturday and Sunday. Temperatures below 1 670 m (5 500 feet) could reach 37–41°C (98–105°F) while higher elevations could reach 32–37°C (90–98°F). Some locations may remain above 32°C (90°F) until sunset.

Extreme Heat Watches cover central and southeastern Montana and north-central Wyoming, with temperatures of 38–42°C (100–108°F) forecast on Saturday.

Parts of north-central Montana could reach 38–43°C (100–110°F). Overnight temperatures there may remain at 21–24°C (70–75°F) from Saturday afternoon through Sunday morning.



Image credit: NOAA/CPC/NWS

The Climate Prediction Center (CPC) said forecast data approaches or exceeds records for warm nighttime temperatures in parts of the Southwest. Warm nights can extend heat exposure after daytime temperatures begin to fall.

The CPC’s outlook for August 7–13 identifies a moderate risk of extreme heat across parts of the West, Great Plains and the Mississippi, Ohio and Tennessee valleys on August 7 and 8.

A slight risk of extreme heat covers most of the contiguous United States during that week. Rapid-onset drought is also possible across parts of the Central and Southern Plains and the Middle and Lower Mississippi Valley.

National Weather Service is advising people in affected areas to stay in air-conditioned buildings when possible, drink water, avoid direct sunlight, check relatives and neighbors, and move strenuous outdoor work to cooler parts of the day.

Children and pets should never be left in unattended vehicles. Anyone showing signs of heat stroke needs emergency medical assistance.

References:
1 Extreme Heat Warning – NWS – July 31, 2026
2 Heat Advisory – NWS – July 31, 2026
3 Short Range Forecast Discussion – NWS/WPC – July 31, 2026

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Rishav Kothari

I am an Assistant Editor and Severe Weather & Science Journalist at The Watchers, specializing in real-time severe weather coverage, geophysical event reporting, and research-driven scientific analysis. You can reach me at rishav(at)watchers(.)news.