Split monsoon season in Tucson ends with a really hot summer

This year’s monsoon in Tucson was split in two: An early, wet start and a dry, especially hot end.

Tucson recorded 5.39 inches of rain in the first half of this year’s monsoon (June 15 to Aug. 8), and just 0.41 inches in the second half (Aug. 9 to to Sept. 30), the National Weather Service here posted on X.

The official monsoon season here spans June 15 to Sept. 30.

In-all, 5.80 inches of rain fell in this year’s monsoon season, 0.11 inches above-normal. It’s the 61st driest such period in Tucson’s weather history, dating back to 1895, the National Weather Service in Tucson says.

And it was hot too.

Tucson had already reached 102 degrees by early Tuesday afternoon, marking the 100th day to reach triple-digit highs this year, said Glenn Lader, a weather service meteorologist. That’s the second-most days to reach at least 100 degrees in a given year, behind 2020, Lader said.

The hottest recorded October high temperature in Tucson — 103 degrees — was was broken later that afternoon as the Tucson International Airport reached 105 degrees “so far,” the national weather service here said in a post on X shortly before 1:30 p.m.

Stormy start to 2024 monsoon

Powerful storms prompted a wetter-than-usual start to the monsoon.

On June 21, a big storm dropped 0.35 inches of rainfall at the airport, a weather service meteorologist told the Star in August.

That sparked a a busy few days of isolated monsoon storms. The storms produced heavy rain, flooding and resulted in the death of a woman whose body was found in the Rillito River near Fort Lowell and Swan roads. Another major storm on July 2, resulted in a tornado on Tucson’s southeast side, but damage was limited.

On July 14, there were two tornado warnings issued when a complex of storms struck the region. Storm damage stretched across the area, including toppled trees, power lines and the roof being ripped off an auto parts store. The complex brought numerous microbursts across the city, with the strongest recorded wind gust reaching 76 mph in the Tucson Mountains.

From the beginning of June through Aug. 15, the Tucson Fire Department responded to 33 calls for swift-water rescues and 49 stranded vehicle calls, the department says. The total figure of 82 combined calls is the most since 2021 when there were 47 water rescues and 40 calls for stranded vehicles, though that included the entire month of August.

Rainy days go away

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The 1.2 inches of rain that fell here in August was 0.78 inches less than the normal. But that figure is a little misleading, because according to the national weather service here, 0.91 inches of rain “occurred on (Aug. 8) at the airport in a span of 30 minutes,” the weather service posted on X.

The Tucson International Airport is where Tucson’s official weather records are measured. The last time there was measurable rain there: Sept. 17, when .01 inches fell.

And it only rained 0.12 inches at the airport for all of September, 1.2 inches below normal.

Heat a factor all season

Wet or dry, heat was a factor for all of Tucson’s monsoon season.

It was the fourth hottest June, second hottest July and sixth hottest August on record. That made summer 2024 tie 2020 as the hottest Tucson summer on record, the weather service says.

Dating back to 1895, the average amount of 100-plus-degree days in the months of June through September is 63 days. Tucson recorded its 93rd triple-digit high on Monday, the final day of the monsoon season.

Through Monday, 44 days topped the 105-degree mark, the third-most in Tucson’s weather history behind 1994’s 53 days and 2020’s 57 days. There are normally 25 such-days in the months of June through September.

Hot days likely to continue

Tucson’s winter is expected to be warmer and drier than usual.

The first-half of October will likely bring above-normal temperatures and below-normal rain, says Lader, the weather service meteorologist.

For the second-half of October, the Climate Prediction Center is placing equal chances on above-, below- or near-normal precipitation.

The region is trending towards a La Niña weather pattern, which tend to be drier. But Lader notes it’s actually trending towards a weak La Niña, and the correlations between it and precipitation “are a little less prevalent” when making longterm rain predictions.

More immediately, high temperatures dropping below 100-degrees will not likely be a regular thing until later in October, Lader said.

“But we’re kind of in this for the time being, this very persistent, hot pattern where we’re seeing the latest hottest temperatures on-record,” he said.

Photos: Monsoon 2024 in Tucson