Arizona Extreme Heat Warning Through August 23: How to Stay Safe, Find Cooling Shelters, and Protect Your Health Outdoors

An Extreme Heat Warning is in effect right now across multiple Arizona communities, issued August 19, 2026, at 10:49 AM MST and running through August 23, 2026, at 8:00 PM MST. The warning covers a broad reach of the state, including Buckeye and Avondale, the Parker Valley, Tonopah Desert, San Carlos, Aguila Valley, the Northwest Valley, Lake Havasu and Fort Mohave, Western Pima County including Ajo and Organ Pipe Cactus National Monument, the Upper Gila River and Aravaipa Valleys including Clifton and Safford, and Grand Canyon Country. The warning has been issued jointly by the National Weather Service offices in Phoenix, Las Vegas, Tucson, and Flagstaff.

What the National Weather Service Is Telling You to Do Right Now

The National Weather Service Phoenix office is direct: an Extreme Heat Warning means that a period of very hot temperatures, even by local standards, will occur, and actions should be taken immediately to lessen its impact. That guidance is not passive. Here is what officials are specifically calling for.

If you work or spend time outdoors, take extra precautions. When possible, reschedule strenuous activities to early morning or evening hours, before heat peaks during the afternoon. Wear lightweight, loose-fitting clothing and drink plenty of water. Know the signs and symptoms of heat exhaustion and heat stroke before you go outside, not after symptoms appear.

For outdoor workers, the NWS alert draws directly from Occupational Safety and Health Administration recommendations: schedule frequent rest breaks in shaded or air-conditioned environments. If anyone is overcome by heat, move them immediately to a cool, shaded location. Heat stroke is a medical emergency. Call 911.

The alert also includes a separate dust hazard instruction worth noting: persons with respiratory problems should make preparations to stay indoors until blowing dust conditions pass. If you encounter blowing dust or blowing sand on a roadway, or see it approaching, pull off the road as far as possible and put your vehicle in park. Turn your lights completely off and keep your foot off the brake pedal. The NWS guidance phrase to remember is simple: “Pull Aside, Stay Alive.”

Public cooling shelters are available in some areas during this warning period. Contact your county officials directly for locations and hours, as availability varies by jurisdiction.

Why This Warning Matters for Preparedness Planning

Extreme heat is the leading weather-related cause of death in the United States, and Arizona’s desert geography means that the risk does not ease after sunset the way it does in other climates. At USRiskRadar, we track sustained hazard patterns across the country, and heat events consistently demand the same foundational response: knowing where your nearest cooling resource is before you need it, having a plan for vulnerable household members including elderly relatives, young children, and pets, and not waiting for symptoms to act. The window between heat exhaustion and heat stroke can be short. The time to locate a shelter, check on a neighbor, or adjust a work schedule is now, while the warning is active and the morning hours still offer a buffer. Check back with your county emergency management office for real-time shelter updates, and monitor NWS Phoenix at weather.gov for any changes to this warning before August 23.

For the fundamentals that apply beyond this specific alert, see our Extreme Heat Preparedness guide.

Source: National Weather Service (NWS Phoenix AZ, NWS Las Vegas NV, NWS Tucson AZ, NWS Flagstaff AZ). Active alert data retrieved 2026-08-19 22:00 UTC via api.weather.gov.