Extreme Heat Warnings issued for parts of Arizona, California and Nevada, temperatures above 49°C (120°F) forecast
Extreme Heat Warnings have been issued across large parts of Arizona, California, and Nevada as a prolonged heat event is forecast to persist through at least Monday, July 27, 2026. Afternoon temperatures are expected to reach 38 to above 49°C (100 to more than 120°F), while exceptionally warm overnight lows are forecast to provide little relief, significantly increasing the risk of heat-related illness.
Mojave Desert, California. Credit: Alexander Hatley
Extreme Heat Warnings remain in effect across large parts of Arizona, California, and Nevada as a prolonged and dangerous heat event is forecast to persist through at least Monday, July 27.
Afternoon temperatures ranging from 38 to above 49°C (100 to more than 120°F) are forecast, with the highest values forecast across Death Valley, the lower Colorado River Valley, southeastern California deserts, and parts of southern Arizona, according to the The National Weather Service (NWS).
Exceptionally warm overnight temperatures are forecast to provide little relief, with lows remaining between the upper 20s and mid-30s°C (80s to mid-90s°F) across many desert locations. The combination of extreme daytime heat and limited overnight cooling is expected to significantly increase the risk of heat-related illness, particularly during prolonged outdoor exposure.
NWS forecast offices warn that Major to locally Extreme HeatRisk conditions are expected across parts of Arizona and southeastern California. Residents are urged to stay hydrated, limit strenuous outdoor activities during the hottest part of the day, use cooling centers where available, and never leave children or pets unattended inside vehicles.
California
Greater Mojave Desert and Death Valley (NWS Las Vegas)
The NWS Las Vegas office continues an Extreme Heat Warning from 10:00 PDT Thursday through 20:00 PDT Monday for southeastern California, including Death Valley National Park, the Eastern and Western Mojave deserts, Morongo Basin, Cadiz Basin, Needles, Baker, Barstow, Twentynine Palms, and surrounding desert communities.
Afternoon temperatures are forecast to reach 42 to 46°C (108 to 114°F) across most desert valleys, exceed 46°C (115°F) along the Colorado River Valley, and approach 49°C (120°F) in Death Valley. Overnight lows are forecast between 27 and 35°C (80 and 95°F), providing little nighttime relief.
Indian Wells Valley and Mojave Desert (NWS Hanford)
An Extreme Heat Warning remains in effect from 08:00 PDT Thursday through 21:00 PDT Monday for the Indian Wells Valley and Mojave Desert, including Ridgecrest, California City, Rosamond, Edwards Air Force Base, Inyokern, and Randsburg.
Afternoon temperatures are forecast between 42 and 44°C (108 and 112°F), with the NWS warning that heat-related illnesses will become significantly more likely during the prolonged event.
Inland Empire (NWS San Diego)
The NWS San Diego office continues an Extreme Heat Warning until 20:00 PDT Monday for the Inland Empire, including San Bernardino, Riverside, Moreno Valley, Corona, Ontario, Fontana, and Rancho Cucamonga.
High temperatures are forecast to reach the upper 30s to 43°C (upper 90s to 110°F), while overnight lows are expected to remain in the low to mid-20s°C (low to mid-70s°F), limiting nighttime recovery through Saturday.
Apple and Lucerne Valleys (NWS San Diego)
An Extreme Heat Warning remains in effect from 10:00 PDT Thursday until 20:00 PDT Monday for Apple Valley, Lucerne Valley, Victorville, and Hesperia.
Afternoon temperatures are forecast between 38 and 43°C (100 and 110°F), while overnight lows remain from the mid-20s to around 31°C (mid-70s to upper 80s°F), contributing to prolonged heat stress.
Coachella Valley, San Diego County deserts and San Gorgonio Pass (NWS San Diego)
The warning remains in effect until 20:00 PDT Monday for the Coachella Valley, San Diego County deserts, and the San Gorgonio Pass.
Temperatures are forecast to reach as high as 49°C (120°F), while overnight lows remain between approximately 31 and 35°C (upper 80s to mid-90s°F). Major to locally Extreme HeatRisk conditions are forecast, with exceptionally warm nights limiting recovery from daytime heat.
San Diego County Mountains (NWS San Diego)
The San Diego County Mountains remain under an Extreme Heat Warning until 20:00 PDT Monday.
Daytime temperatures are forecast to reach the mid-30s to around 38°C (mid-90s to low 100s°F), while overnight temperatures remain in the low-20s°C (70s°F), maintaining elevated heat stress throughout the event.
Antelope Valley (NWS Los Angeles/Oxnard)
The NWS Los Angeles/Oxnard office continues an Extreme Heat Warning from 10:00 PDT Thursday through 20:00 PDT Monday for Antelope Valley, including Lancaster, Palmdale, and Lake Los Angeles.
Afternoon temperatures are forecast between 38 and 42°C (100 and 108°F). Unusually warm overnight conditions are expected to limit nighttime cooling, with the highest risk of dangerous heat illness among young children, older adults, people without access to air conditioning, and anyone spending extended periods outdoors.
Arizona
South-central Arizona and Phoenix metropolitan area (NWS Phoenix)
The NWS Phoenix office continues an Extreme Heat Warning from 10:00 MST Thursday through 20:00 MST Monday for the following areas: south-central Arizona, including Aguila Valley, the Tonopah Desert, Gila Bend, Cave Creek, New River, Fountain Hills, East Mesa, Superior, Apache Junction, parts of Pinal County, the Sonoran Desert National Monument, and the Phoenix metropolitan area, including Phoenix, Mesa, Tempe, Chandler, Gilbert, Scottsdale, Paradise Valley, Glendale, Deer Valley, Goodyear, Avondale, Queen Creek, Surprise, Peoria, and neighboring communities.
Afternoon temperatures are forecast to reach 41 to 48°C (105 to 118°F), with the hottest conditions expected across the metropolitan area. Major HeatRisk is forecast throughout the warning area, significantly increasing the risk of heat-related illness during prolonged outdoor exposure.
Lower Colorado River Valley, La Paz County and southeast Yuma County (NWS Phoenix)
Another Extreme Heat Warning remains in effect from 10:00 PDT Thursday through 20:00 PDT Monday for central La Paz County, southeast Yuma County, the Gila River Valley, Kofa National Wildlife Refuge, Joshua Tree National Park, Yuma, Parker Valley, Blythe, the Imperial Valley, the Salton Sea region, Palo Verde Valley, Chuckwalla Valley, and surrounding desert communities.
Afternoon temperatures are forecast between 39 and 48°C (103 and 119°F), with the highest values expected across the lower Colorado River Valley. Major to Extreme HeatRisk conditions are forecast throughout much of the region.
Globe, Miami, San Carlos and Tonto Basin (NWS Phoenix)
An additional Extreme Heat Warning is scheduled from 10:00 MST Friday through 20:00 MST Saturday for Globe, Miami, San Carlos, Tonto Basin, and surrounding communities.
Afternoon temperatures are forecast between 39 and 44°C (103 and 112°F), with Major HeatRisk and an increasing potential for heat-related illness.
Lower Grand Canyon (NWS Flagstaff)
The NWS Flagstaff office has issued an Extreme Heat Warning from 10:00 MST Friday through 20:00 MST Sunday for elevations below 1 220 m (4 000 feet) within Grand Canyon National Park.
Temperatures are forecast to reach around 41°C (105°F) at Havasupai Gardens and 44 to 46°C (112 to 114°F) at Phantom Ranch.
The NWS notes that this warning is reserved for the hottest days of the year and advises day hikers not to descend more than 1½ miles below the Bright Angel Trailhead. Hikers are encouraged to avoid strenuous activity between 10:00 and 16:00, carry sufficient water, electrolyte supplements, salty snacks, sunscreen, and appropriate sun protection.
Marble and Glen Canyons (NWS Flagstaff)
A separate Extreme Heat Warning remains in effect from 10:00 MST Friday until 20:00 MST Sunday for Marble and Glen Canyons, including Lees Ferry and Page.
Daytime temperatures are forecast to reach 41 to 43°C (105 to 110°F), increasing the risk of heat-related illness during prolonged outdoor exposure.
Tucson metropolitan area and western Pima County (NWS Tucson)
The NWS Tucson office maintains an Extreme Heat Warning from 10:00 MST Friday through 20:00 MST Saturday for the Tucson metropolitan area, western Pima County, the Tohono O’odham Nation, southeastern Pinal County, and the Upper Gila River Valley.
Temperatures are forecast to reach 41 to 44°C (105 to 112°F), while overnight lows between 28 and 31°C (82 and 88°F) are expected to provide little or no overnight cooling, particularly across western desert locations. Major HeatRisk is forecast throughout the warning period.
Upper Santa Cruz River Valley and eastern Cochise County (NWS Tucson)
A second Extreme Heat Warning covers the Upper Santa Cruz River Valley, Upper San Pedro River Valley, and eastern Cochise County below 1 524 m (5 000 feet), including Benson, Sierra Vista, Nogales, Douglas, and Willcox, from 10:00 MST Friday through 20:00 MST Saturday.
Afternoon temperatures are forecast between 38 and 41°C (100 and 105°F), significantly increasing the risk of heat-related illness.
Nevada
Southern Nevada (NWS Las Vegas)
The NWS Las Vegas office continues an Extreme Heat Warning from 10:00 PDT Thursday through 20:00 PDT Monday for southern Nevada, including the Las Vegas Valley, Henderson, North Las Vegas, Boulder City, Lake Mead, Lake Mohave, Laughlin, and surrounding communities.
Afternoon temperatures are forecast to reach 42 to 46°C (108 to 114°F) across most desert valleys, while areas along the Colorado River Valley are forecast to exceed 46°C (115°F). Overnight lows are expected to remain between 27 and 35°C (80 and 95°F), providing little nighttime relief.
References:
1 WWA Summary of Extreme Heat Warning – NWS – July 23, 2026
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.
Commenting rules and guidelines
We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules.