A sub-90-degree day in Tucson this weekend? Maybe

Slightly cooler temperatures have slowly crept back into Tucson over the past few days.

And there’s a chance — a sliver of one — that could be an even bigger temperature change: a day this weekend below 90 degrees.

It’s unlikely, but possible.

Sunday’s high is forecast to be 93 degrees.

But, due to a week of rain storms and cloud cover, the National Weather Service in Tucson has placed a 12% to 15% chance on a sub-90-degree Sunday.

That would be the first occurrence of a high temperature in the 80s since June 1.

August 7 marked the first time in nearly two months Tucson’s high fell below 100 degrees, ending a 53-day streak that began on June 16.

Beginning on Saturday, high temperatures are expected to drop to 97 degrees due to the week’s cloud cover, something NWS Tucson meteorologist Lance Tripoli says is a “dominant factor” in determining whether Sunday can stay below 90 degrees.

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“When it’s wet, the temperature doesn’t go as high because the water vapor is a great absorber for heat … it will just draw heat from the air to evaporate the water on the ground,” Tripoli says. “Whatever attempts the sun makes to try to warm the air, that moisture is going to absorb a lot of that heat,” Tripoli said.

While a break from blazing temperatures will certainly be welcome, Tripoli warns of potential dangers of heat exposure, even when temperatures fall just below triple digits.

“When dew points are higher, when we typically see higher temperatures in the summer, there’s going to be higher relative humidity,” he said. “It’s going to be hard to wick the heat from your body when the air becomes moist … that’s definitely a concern, especially when there’s no wind or light winds.”

Even with the expected temperatures this weekend, Tripoli still suggests Tucsonans should treat it like they have all summer: stay indoors from late-mornings to late afternoon; drink plenty of water; and to try and get outdoor activity and work done prior to 10 a.m.

The forecast for Monday and Tuesday predict highs of at least 100 degrees.

Meanwhile, the weather service on Tuesday issued an excessive heat warning for Maricopa and Yuma counties from Aug. 15 to17, and for La Paz and Pinal counties from Aug. 16 to 17.