Today's high in Tucson expected to be 18 degrees lower than yesterday's

That's a big plunge from Thursday's high of 103. (At 11 o'clock last night it was still 82, nearly as warm as today's forecasted high.) 

Credit the moisture and cloud cover for the drop, as the National Weather Service says there's also an 80% chance of rain today — and a 36% probability that more than 1 inch will fall at Tucson International Airport, where the city's official weather readings are recorded. 

Because heavy rainfall might flood washes and roads, there's a flash flood watch through 12 a.m. Saturday, the weather service warns. 

We had a high of 89 on Aug. 19, but otherwise, Tucson hadn't had highs in the 80s since about the first week of June, says weather service meteorologist Aaron Hardin.

The normal high for this time of year is 98, he says.

Saturday is expected to see a high of 90 with a 40% chance of showers and thunderstorms.

Backyard grills might stay dry for the rest of the holiday weekend, though, as sunny days and highs of 94 on Sunday and 96 on Labor Day are predicted.