An Extreme Heat Warning is in effect right now for a large portion of Arizona, covering the following areas: New River Mesa, Kofa, Northwest Valley, Parker Valley, Aguila Valley, Northwest Plateau, Marble and Glen Canyons, Northern Gila County, Grand Canyon Country, Yavapai County Valleys and Basins, and Western Pima County including Ajo and Organ Pipe Cactus National Monument. The warning became active on Monday, July 28, 2026, at 1:56 PM MST and runs through Sunday, August 2, 2026, at 8:00 PM MST. The alert was issued jointly by the National Weather Service offices in Phoenix, AZ; Las Vegas, NV; Flagstaff, AZ; and Tucson, AZ, reflecting the broad geographic scope of the dangerous heat event.
According to the National Weather Service, an Extreme Heat Warning means that a period of very hot temperatures, even by local standards, will occur. This is not routine summer heat. Residents and visitors across all affected zones should treat this warning seriously and take immediate steps to reduce their exposure.
What NWS Is Telling You to Do Right Now
The National Weather Service is directing anyone who works or spends time outdoors to take extra precautions for the duration of this warning. Where possible, strenuous outdoor activities should be rescheduled to early morning or evening hours, when temperatures are lower. Residents are advised to wear lightweight, loose-fitting clothing and to drink plenty of water throughout the day.
Knowing the signs and symptoms of heat exhaustion and heat stroke is critical during this period. Heat stroke is classified as a medical emergency. If someone is overcome by heat, they should be moved immediately to a cool, shaded location. If heat stroke is suspected, call 9-1-1 without delay.
For those who work outdoors professionally, the NWS alert specifically references guidance from the Occupational Safety and Health Administration (OSHA), which recommends scheduling frequent rest breaks in shaded or air-conditioned environments. Employers and workers in affected counties should treat these recommendations as a baseline, not an option, for the length of this warning.
Public cooling shelters are available in some areas across the affected region. The NWS advises residents to contact their county officials directly for specific locations and hours. If you or someone in your household does not have reliable air conditioning, identifying a cooling shelter near you before conditions worsen is a practical and potentially life-saving step.
Connecting This Alert to Your Preparedness Plan
Extreme heat is one of the leading weather-related causes of death in the United States, and the Desert Southwest faces this risk more acutely than most regions. At USRiskRadar, we track active NWS alerts precisely because the window between a warning being issued and conditions becoming dangerous can be very short. If you live in or plan to travel through any of the areas listed above between now and August 2, reviewing your heat safety plan, checking on neighbors and family members who may be vulnerable, and confirming access to a cool environment are all concrete actions you can take right now. The NWS Phoenix AZ office will issue updates if conditions change, and we will reflect any significant revisions to this alert as they become available.
For the fundamentals that apply beyond this specific alert, see our Power Outage Preparedness guide.
Source: National Weather Service (NWS Phoenix AZ, NWS Las Vegas NV, NWS Flagstaff AZ, NWS Tucson AZ). Active alert data retrieved 2026-07-28 22:00 UTC via api.weather.gov.
