An Extreme Heat Warning is in effect across a wide stretch of Arizona on August 29, 2026, from 9:39 a.m. MST through 8:00 p.m. MST. The warning covers communities including Nogales and the Upper Santa Cruz River and Altar Valleys, Kearny, Mammoth, and Oracle in Southeast Pinal County, Ajo and Organ Pipe Cactus National Monument in Western Pima County, the Northwest Valley, San Carlos, South Mountain and Ahwatukee, Gila Bend, Parker Valley, and Aguila Valley. The alert was jointly issued by the National Weather Service offices in Tucson, Arizona and Phoenix, Arizona.
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If you are in any of the listed areas, this warning is active right now and covers the hottest hours of the afternoon. Conditions during an Extreme Heat Warning are serious enough that ordinary precautions are not sufficient. Here is what the affected communities need to know while this alert is in force.
What NWS Is Directing Residents and Workers to Do Right Now
The National Weather Service Tucson and Phoenix offices are placing particular emphasis on outdoor workers. Per the alert, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air-conditioned environments. If you supervise a crew, this is not optional guidance: structure your shifts around it through 8:00 p.m. MST.
For anyone who must be outside, the NWS instruction is direct: reschedule strenuous activities to early morning or evening whenever possible. Wear lightweight, loose-fitting clothing. Drink plenty of water. These steps reduce the body’s heat load before symptoms begin.
Knowing the difference between heat exhaustion and heat stroke matters right now because the response to each is different. Heat stroke is classified as a medical emergency. The NWS alert is explicit: anyone overcome by heat should be moved immediately to a cool, shaded location, and 9-1-1 should be called. Do not wait to see if the person improves on their own. Heat stroke can cause permanent injury or death within minutes without emergency intervention.
Heat exhaustion symptoms, which often precede heat stroke, include heavy sweating, weakness, cold or pale skin, a fast or weak pulse, nausea, and possible fainting. If you or someone nearby shows these signs during the warning window, stop activity immediately, move to a cool environment, and apply cool, wet cloths to the skin. If symptoms worsen or the person loses consciousness, call 9-1-1.
The coverage area for this warning is geographically diverse, from urban neighborhoods like South Mountain and Ahwatukee to remote areas including Organ Pipe Cactus National Monument and Aguila Valley. Visitors and hikers in the monument area face particular risk because evacuation and emergency response times are longer in remote desert terrain. If you are planning any outdoor recreation in those zones on August 29, 2026, the NWS guidance to shift activity to early morning or evening is the most actionable step you can take before conditions peak.
Connecting This Warning to Year-Round Preparedness
Extreme heat events like this one are part of a broader pattern that Arizona communities navigate every summer, and they share a common preparedness foundation with the wildfire risk that has driven 35 of the 55 federal disaster declarations in the past 60 days across states including Arizona’s neighbors Washington, Oregon, Nevada, and Colorado. Both hazards stress the same household readiness basics: know your evacuation or shelter plan before you need it, keep a water supply that does not depend on a single source, and have a communication plan for family members who may be in different locations, including remote worksites or schools. The skills built around one hazard transfer directly to the other. Using the current Extreme Heat Warning as a prompt to review those fundamentals now, while the alert is active and the risk is concrete, is exactly the kind of preparedness action that reduces harm when the next event arrives.
Monitor updates from the National Weather Service Tucson at weather.gov/tucson and NWS Phoenix at weather.gov/psr through 8:00 p.m. MST on August 29, 2026 for any changes to this warning.
For the fundamentals that apply beyond this specific alert, see our Extreme Heat Preparedness guide.
Source: National Weather Service (NWS Tucson AZ, NWS Phoenix AZ). Active alert data retrieved 2026-08-29 22:00 UTC via api.weather.gov.
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