Arizona Extreme Heat Warning August 28-29: How to Work Outside Safely and Recognize a Heat Emergency

An Extreme Heat Warning is in effect right now across multiple regions of Arizona, running from 2:00 PM MST on Friday, August 28, 2026, through 8:00 PM MST on Saturday, August 29, 2026. The warning covers a broad sweep of the state, including Western Pima County (Ajo and Organ Pipe Cactus National Monument), the Upper Santa Cruz River and Altar Valleys including Nogales, San Carlos, the Northwest Valley, Aguila Valley, Tonto Basin, Parker Valley, Yavapai County Valleys and Basins, Grand Canyon Country, and the Lake Havasu and Fort Mohave area. The alert was issued jointly by the National Weather Service offices in Tucson, Phoenix, Flagstaff, and Las Vegas.

What Officials Are Telling You to Do Right Now

The National Weather Service, Tucson office, is directing residents and workers to take extra precautions for the full duration of this warning. If you have any flexibility in your schedule, move strenuous outdoor activities to early morning or evening hours, when temperatures are lower. If outdoor work cannot be rescheduled, the NWS guidance references the Occupational Safety and Health Administration’s recommendation to schedule frequent rest breaks in shaded or air-conditioned environments. That is not a suggestion to consider later. It is the primary heat-illness prevention tool available to outdoor workers during a warning at this level.

Clothing matters. Wear lightweight, loose-fitting clothing when conditions allow, and drink plenty of water throughout the day. Do not wait until you feel thirsty, because thirst is a late indicator of dehydration in extreme heat conditions.

Know the difference between heat exhaustion and heat stroke, because the response is different. Heat exhaustion can often be managed by moving the person to a cool, shaded location and providing water. Heat stroke is a medical emergency. The official NWS guidance is direct on this point: if someone is overcome by heat, move them immediately to a cool and shaded location, then call 9-1-1. Heat stroke requires emergency medical care and cannot be managed at home.

Signs of heat stroke include a body temperature above 103 degrees Fahrenheit, hot and red skin that may be dry or damp, a rapid and strong pulse, and possible unconsciousness. Do not leave a person showing these signs unattended while waiting for emergency services to arrive.

Connecting This Warning to Year-Round Preparedness

Extreme heat is the deadliest weather hazard in the United States on an average annual basis, and the Southwest faces it with particular intensity each summer. At USRiskRadar, we track both acute events like this warning and the longer-term, sustained risks that shape disaster preparedness across the country, including wildfire, which has driven 36 of the 56 federal disaster declarations in the past 60 days, with Washington, Oregon, Nevada, and Colorado among the hardest-hit states. Heat and fire often move together in the West, so if you are in an Arizona area under this warning and are also near fire-prone terrain, this is a good moment to confirm that your household evacuation plan is current and that any go-bag essentials are accessible. Acute warnings like this one are a practical prompt to pressure-test the broader preparations that protect you across the full season, not just on any single afternoon.

This article is based on an active alert issued by the National Weather Service. For the most current warning status and any extensions or cancellations, check weather.gov or the NWS Tucson, Phoenix, Flagstaff, and Las Vegas offices directly.

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, NWS Flagstaff AZ, NWS Las Vegas NV). Active alert data retrieved 2026-08-28 22:01 UTC via api.weather.gov.