Extreme Heat Warning Covers Tucson As First Monsoon Moisture Arrives

TUCSON, AZ — Tucson is heading into a stretch of extreme heat this week just as the first meaningful monsoon moisture of the season moves into Southern Arizona.

An Extreme Heat Warning is in effect from 10 a.m. Tuesday through 8 p.m. Wednesday for lower elevations in the Tucson area and west, along with Graham County near the Gila River, according to the National Weather Service in Tucson.

Temperatures through Tuesday and Wednesday are expected to run 3 to 8 degrees above normal, with areas of major heat risk in the lower elevations.

Forecasters said the weather pattern should gradually cool after Thursday, but not before Tucson sees dangerous heat paired with a growing chance of thunderstorms.

The added moisture began moving into the region overnight, setting up what forecasters called the season’s first meaningful monsoon push.

Storms are expected to develop as early as noon to 1 p.m. Monday, first over the White and Chiricahua mountains. From there, they could move as far west as the eastern edges of Pima and Santa Cruz counties, with forecasters watching those western boundaries through the afternoon.

The biggest concern from today’s storms is not rainfall. Instead, the weather setup points to strong winds and blowing dust.

Thunderstorms could produce gusts above 50 mph, and wind gust probabilities of 50 to 90 percent are centered from the Catalina Mountains eastward, according to the weather service.

Blowing dust could also move into Cochise County this evening from storms forming in New Mexico.

While some surface moisture is in place, the weather service said it is not enough to make flash flooding a major concern today.

That could change later in the week. Moisture is expected to increase each day, and the storm window is forecast to expand westward.

Gusty winds and blowing dust remain the main threats Tuesday and Wednesday, while the risk of flash flooding is expected to rise later in the week as deeper moisture arrives.

There is also a seasonal footnote on the calendar. At 10:30 a.m. Monday, Earth reaches aphelion, its farthest point from the sun, at about 94.5 million miles away.

The timing does not bring cooler weather to Tucson, but it does serve as a reminder that summer heat is not driven by how close Earth is to the sun.