An Extreme Heat Warning is currently in effect across a broad stretch of Arizona, covering the following areas: Northwest Valley, Aguila Valley, Parker Valley, Tonto Basin, Grand Canyon Country, Marble and Glen Canyons, Western Pima County including Ajo and Organ Pipe Cactus National Monument, Upper Santa Cruz River and Altar Valleys including Nogales, and Lake Havasu and Fort Mohave. The warning was issued on July 24, 2026, at 2:21 PM MST and remains in effect through July 27, 2026, at 8:00 PM MST. The alert was issued jointly by NWS Phoenix AZ, NWS Flagstaff AZ, NWS Tucson AZ, and NWS Las Vegas NV.
What the National Weather Service Is Telling You Right Now
According to the National Weather Service, an Extreme Heat Warning means that a period of very hot temperatures, even by local standards, is occurring, and that actions must be taken to lessen its impact. This is not routine summer heat; the language used by NWS Phoenix AZ specifically signals conditions that exceed what residents in these already hot regions typically experience.
If you work or spend time outdoors, the National Weather Service urges you to take extra precautions. Where possible, reschedule any strenuous physical activity to early morning or evening hours when temperatures are lower. If you must be outside during peak heat, wear lightweight, loose-fitting clothing and drink plenty of water continuously, do not wait until you feel thirsty.
The NWS alert specifically highlights guidance from the Occupational Safety and Health Administration (OSHA), which recommends that outdoor workers take frequent rest breaks in shaded or air-conditioned environments. Employers and workers across the affected Arizona counties should treat this recommendation as an operational requirement for the duration of the warning.
Knowing the signs of heat exhaustion and heat stroke is critical right now. Anyone who appears overcome by heat should be moved immediately to a cool, shaded location. Heat stroke is a medical emergency, call 9-1-1 immediately. Do not attempt to manage heat stroke symptoms at home or delay seeking emergency help.
Public cooling shelters are available in some areas covered by this warning. The NWS advises consulting your county officials directly for specific shelter locations and hours. If you or someone in your household lacks reliable air conditioning, locating the nearest cooling shelter before temperatures peak is a practical and potentially life-saving step.
Connecting This Alert to Your Preparedness Plan
Extreme heat is consistently one of the deadliest weather-related hazards in the United States, and events like this warning, spanning large, geographically diverse sections of Arizona, are precisely the scenario that preparedness planning is designed for. At USRiskRadar, we encourage households in heat-prone regions to maintain a standing list of local cooling resources, keep emergency contacts current, and check regularly on neighbors, elderly family members, and anyone without adequate cooling. The infrastructure for surviving extreme heat events exists in most communities; knowing where it is before a warning is issued makes it far more likely you’ll use it when it counts. With this warning running through the evening hours of July 27, 2026, there is still time to act, plan, and look out for those around you.
Source: National Weather Service Phoenix AZ, Flagstaff AZ, Tucson AZ, and Las Vegas NV. Always refer to weather.gov for the latest official updates on this warning.
For the fundamentals that apply beyond this specific alert, see our Power Outage Preparedness guide.
Source: National Weather Service (NWS Phoenix AZ, NWS Flagstaff AZ, NWS Tucson AZ, NWS Las Vegas NV), active alert data retrieved 2026-07-24 22:00 UTC via api.weather.gov.
