An Extreme Heat Warning is in effect right now across a broad swath of Arizona, covering the Northwest Plateau, New River Mesa, Aguila Valley, Parker Valley, Northwest Valley, Kofa, Western Pima County including Ajo and Organ Pipe Cactus National Monument, Grand Canyon Country, Northern Gila County, and Marble and Glen Canyons. The warning became effective on Thursday, July 31, 2026, at 2:56 PM PDT and runs through Saturday, August 2, 2026, at 8:00 PM PDT. The alert was jointly issued by the National Weather Service offices in Las Vegas NV, Phoenix AZ, Tucson AZ, and Flagstaff AZ, reflecting the geographic reach of this heat event across the state.
This is not a watch or an advisory. A warning at this level means dangerous, potentially lethal heat conditions are occurring or imminent across all of the listed areas. Residents, travelers, and workers in these zones should treat the next 48-plus hours as a period requiring active precaution, not passive awareness.
What the National Weather Service Is Telling You to Do Right Now
The National Weather Service is direct in its guidance: drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check on relatives and neighbors. That last point matters. Heat emergencies often claim lives precisely because the person in danger is alone or isolated. A phone call or a knock on the door can save a life.
Do not leave young children or pets in unattended vehicles. Car interiors reach lethal temperatures within minutes, even with windows cracked. This risk does not diminish with a short errand or a quick stop. If you are traveling with children or animals, they come with you, every time, without exception.
For anyone who must be outdoors, the NWS recommends wearing lightweight and loose-fitting clothing and limiting strenuous activity to early morning or evening hours when temperatures are lower. If you observe someone showing signs of heat exhaustion or heat stroke, act immediately. Move them to a cool, shaded location. Heat stroke is a medical emergency. Call 911.
Outdoor workers face elevated risk during a warning of this duration. The National Weather Service specifically references guidance from the Occupational Safety and Health Administration (OSHA), which recommends scheduling frequent rest breaks in shaded or air-conditioned environments throughout the workday. Employers operating job sites in the affected areas should review those protocols now, before shifts begin, not after someone collapses.
Monitor updated forecasts directly through the NWS offices listed above. Conditions and boundaries can shift, and the warning period extends well into Saturday evening.
Connecting This Warning to Your Broader Preparedness
Extreme heat is the deadliest weather hazard in the United States on an annual basis, and Arizona’s geography makes events like this one a recurring reality rather than a rare outlier. At USRiskRadar, our evergreen guidance on heat preparedness covers the full preparedness cycle: identifying cooling centers in advance, building a household communication plan for checking on vulnerable neighbors, and understanding the physical signs of heat illness before an emergency develops. The actions the NWS is recommending right now, hydration, shade, air conditioning access, and buddy checks, are the same core behaviors that preparedness planning reinforces year-round. If this warning has caught you without a plan, use the next 48 hours to build one. The next event will not wait for a convenient moment.
For the fundamentals that apply beyond this specific alert, see our Extreme Heat Preparedness guide.
Source: National Weather Service (NWS Las Vegas NV, NWS Phoenix AZ, NWS Tucson AZ, NWS Flagstaff AZ). Active alert data retrieved 2026-07-31 22:00 UTC via api.weather.gov.
