A midweek surge of searing temperatures has prompted the National Weather Service to upgrade its alert for the Phoenix area to an extreme heat warning, projecting dangerous conditions from late Tuesday morning through Thursday evening. The agency warned that a large high-pressure system will push afternoon readings well above seasonal norms, with forecasters forecasting highs around 114 degrees for Tuesday, Wednesday and Thursday and overnight lows generally between 85 and 90.
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The warning replaces an earlier extreme heat watch and is scheduled to be in effect from 10 a.m. Tuesday until 8 p.m. Thursday. Meteorologists said the extended stretch of daytime heat will likely create areas of major heat risk across the lower deserts and parts of higher terrain, heightening concerns for heat-related illness among residents who are outdoors, lack adequate cooling or are otherwise vulnerable to extreme temperatures.
National Weather Service graphic labeled 'Major Heat Risk - Extreme Heat Watch' for the Phoenix region, showing forecast afternoon highs of 103–110°F and safety tips for residents.
The forecasted highs represent a marked rise above the typical mid-summer benchmark for Phoenix: the normal high this time of year is about 107 degrees. So far this season the city has reached 112 degrees on June 16 and again on June 26, but the midweek spike will push many neighborhoods and valley locations into new territory for 2026 if the projected highs materialize.
Public safety measures tied to extreme heat warnings take effect across the city. Daytime closures of popular municipal hiking trails, including Camelback Mountain, Piestewa Peak and South Mountain, are triggered when the warning is active, forcing outdoor recreation enthusiasts to alter plans during peak heat hours. Parks and recreation officials have increasingly relied on these shutdowns as a blunt tool to limit heat exposure on steep, exposed trails where rescue calls rise sharply during extreme temperatures.
City of Phoenix trailhead sign with a prominent 'Heat Warning' poster advising hikers to avoid midday heat — illustrating local precautions as temperatures soar.
Health officials and emergency responders urged residents to take standard heat-safety precautions: drink plenty of water, wear lightweight clothing, avoid strenuous outdoor activity during the hottest parts of the day and seek air-conditioned spaces when possible. The National Weather Service graphic accompanying its alert also highlights safety steps for the public to reduce the risk of heat-related illnesses.
Following the heat spike, forecasters say the atmospheric pattern will shift enough to allow for increased moisture and the first hints of monsoon activity. Mark O’Malley, a meteorologist with the National Weather Service in Phoenix, said Monday that residents should expect some increase in humidity and the possibility of isolated thunderstorms, particularly over higher terrain.
"We will look at some increasing moisture later this week and weekend," O’Malley said. "Probably not everyone will see rain out of this, but there will be a few thunderstorms around in the high terrain. So, we’ll see increased moisture with increased wind gusts coming into the lower elevations of south-central Arizona late this week and into next week."
Despite those signals, forecasters cautioned that any rainfall will likely be spotty rather than widespread. The official observation site used for Phoenix's climate records, Sky Harbor International Airport, last recorded measurable rain on March 29. Monsoon season officially runs from June 15 through Sept. 30, but early-season dry stretches are common and it is not unusual for the valley to go weeks without measurable precipitation even after the season has technically begun.
Residents and visitors should remain aware of the extreme heat warning window and plan accordingly. Cooling centers, water and shade can help reduce immediate risks to those without access to air conditioning. Authorities continue to monitor conditions and will issue updates if the forecast changes or if additional advisories become necessary as the high-pressure system evolves and any monsoon moisture attempts to move into the region.
By Tuesday afternoon, the National Weather Service reported highs above 110°F in Phoenix, Yuma and El Centro, with forecasts indicating a peak near 115°F on Wednesday before a slight cooldown. @NWSPhoenix noted the pattern will support continued major heat risk across the region.
Arizona’s statewide heat portal (HEAT.AZ), maintained by the Arizona Department of Health Services, lists Extreme Heat Warnings across multiple counties — Coconino (July 6–8); Graham, Greenlee and Pima (July 7–8); and Gila, La Paz, Maricopa, Pinal and Yuma (July 7–9) — and notes daytime highs in some areas could reach as high as 117°F.
The City of Phoenix operates a regional heat‑relief network of more than 60 sites, including a 24/7 heat‑respite center at 20 W. Jackson St. and two extended‑hours cooling centers (Justa Center and Cholla Library); residents who need transportation to a cooling center can call 2‑1‑1 for assistance.
Maricopa County confirmed its first heat‑related death of 2026 on April 10 and has repeatedly urged residents to prioritize heat safety and check on older adults, children and people with chronic health conditions.
Local utility policies provide extra protection during extreme heat: Arizona Public Service has agreed not to disconnect customers when temperatures reach 95°F or higher, and Salt River Project suspends shut‑offs in July, August and any other time an extreme heat warning is issued.
On days when the National Weather Service issues an Extreme Heat Warning, popular Phoenix trails (including Camelback Mountain, Piestewa Peak and South Mountain) are closed from 8 a.m. to 5 p.m., and city rules prohibit dogs on trails when temperatures reach 100°F.