After a Fourth of July that felt like typical summer warmth for the area, the Phoenix metro is preparing for a sharp rise in temperatures as a strong ridge of high pressure moves into the region from the east. The pattern, described by local forecasters as a robust dome of high pressure, is expected to push daytime readings higher later this week and into next week, increasing the likelihood of hazardous heat for residents and visitors across the Valley.
Meteorologists tracking the pattern have pointed to two primary drivers behind the warming trend. First is the building ridge of high pressure itself, which suppresses cloud cover and allows daytime heating to intensify. Second is a dry air mass over the Southwest that will limit moisture and the moderating effects that humid or unstable air can bring. Together, those elements are expected to produce hotter and drier conditions than the area has seen through the recent holiday weekend.
Meteorologist highlights a strong ridge over the Southwest labeled “MILD,” a pattern the story says will push temperatures higher in Phoenix later this week.
Local forecasts released in the run-up to the holiday showed some variability through the weekend. Highs were held down somewhat on Saturday because of mostly cloudy skies, with Phoenix forecast at about 105 degrees — a number that would represent a below-average Fourth of July daytime temperature for the city. Those cloud layers also affected nighttime cooling, and forecasters noted that the relatively pleasant overnight lows in the 70s seen earlier may be coming to an end for the foreseeable future.
A satellite moisture-flow graphic used by forecasters highlighted the dry airmass over the Southwest at midafternoon on Monday, reinforcing expectations for less humidity and clearer skies as the ridge strengthens. The setup, forecasters say, supports hotter, drier conditions across the Valley as the week progresses and into the following week, when even higher readings are possible.
Moisture-flow satellite graphic showing dry air over the Southwest at 3:00 PM Monday — a setup that supports hotter, drier conditions across the Valley.
Several forecast runs issued over the holiday weekend and in the days since have tracked a continued rise in temperatures. Some of those outlooks showed highs approaching or reaching the lower 110s for the Phoenix area over the coming days, and one forecast discussion cited the potential for readings as high as 114 degrees in Phoenix next week. Forecasters emphasized that the increase would be driven by the entrenched ridge and the accompanying dry airmass already moving into the region.
The holiday weekend itself was expected to remain warm statewide, with periods of high clouds most notable in southern parts of Arizona. Those clouds moderated daytime highs in places at times but also limited nocturnal cooling, meaning overnight lows were expected to trend up. For metro Phoenix, those nighttime readings are forecast to cease falling into the 70s, with lows through the weekend expected to hold in the mid-80s.
Paul Horton delivered the First Alert forecast updates, tracking the evolving pattern and flagging the potential for extreme heat as the week progresses. Forecasts updated around the holiday noted that while Saturday’s cloud cover kept daytime temperatures a bit lower, the broad synoptic pattern was shifting toward a warmer, drier regime driven by the incoming high-pressure ridge. Residents and city services are being kept apprised of the change in conditions as models continue to refine timing and peak temperatures for the area in the days ahead.
As the pattern evolves, forecasts will continue to be updated to reflect model guidance and observational data. For now, the combination of a strengthening ridge and an expansive dry air mass over the Southwest points toward several days of above-average heat for Phoenix and the surrounding valley, with overnight temperatures remaining elevated and daytime measurements climbing well into the 100s as the region moves deeper into the summer heat cycle.
The National Weather Service has issued an Extreme Heat Watch for the Phoenix Valley from Tuesday morning through Thursday evening, with highs forecast to reach 111-113 degrees and overnight lows staying in the upper 80s. AZFamily and local forecasters are urging residents to prepare for the dangerous conditions by staying hydrated, limiting outdoor activity during peak heat, and checking on at-risk neighbors.
The City of Phoenix opened its heat‑relief network on May 1, 2026, including a 24/7 respite center at 20 W. Jackson St. that will remain open through September 30, plus other cooling locations such as the Justa Center (cooling center open 3–9 p.m. daily) and Cholla Library with extended evening hours.
Maricopa County Department of Public Health confirmed the first heat‑related death of the 2026 season in April 2026 (an older adult male) and is urging residents to use the county and regional Heat Relief Network and available cooling sites.
On April 15, 2026 the Arizona Attorney General announced a $7 million settlement with Arizona Public Service that requires APS to reinstate a voluntary policy halting residential power disconnections when forecasted high temperatures are expected to reach 95°F or above the following day and to fund consumer protections and credits.
Researchers at Arizona State University have found that air‑cooled data centers in the Phoenix area can raise local temperatures by as much as about 4°F downwind of facilities, a factor experts warn can exacerbate urban heat and increase cooling demand.