By John Simpson

The September 2021 and full monsoon Climate report by John Simpson. September, the last month of the monsoon, typically yields highly variable rainfall in the area as the summer thunderstorms come to a close.

September 2021 was no different as many parts of the Tucson area recorded below average precipitation for the month, mainly west of I-10, while other places recorded above average precipitation, mainly in North-Central Tucson to the Catalina Foothills. The heavy rains of July and August did not carry through to September. I recorded 1.24” of rain in central Del Lago, which is below my 11-year average of 1.93” and the Tucson airport recorded 0.71” of rain, below its 30-year average of 1.32.” The hot spot for the Vail area was north of Old Spanish Trail where over 2” of rain fell. For the Tucson metro area, the Sunrise and Swan area was the hot spot with over 3” reported while areas West of I-10 only had .2 to .4.”

On the temperature side, the Tucson airport recorded the 16th warmest September with daytime highs running 0.8 degrees warmer than the average, but nighttime lows running 0.3 degrees cooler than average. Now, for the full monsoon rainfall report. I recorded 19.30” of rain for the monsoon, which is my wettest since I have been keeping records, and well above my 11-year average of 8.17.” The incredible amount of rain recorded this season bumped my average up about 1 full inch. The Tucson airport recorded 12.79,” which is well above its 30-year average of 5.69,” and the 3rd wettest monsoon season since records began in 1894. Monsoon season rainfall for the Vail area varied from 12 to 22” with the heaviest falling right down the center along Colossal Cave / Wentworth, and Camino Loma Alta from Sahuarita Road to Old Spanish Trail, with the lower amount to the East (Mescal) and West (Rita Ranch). For the Tucson metro area, rainfall varied from about 9 to 22” with the lower amounts West and higher amounts along the foothills and East side against the Rincons and Vail.

This monsoon season was one for the record books. Below are some monsoon rainfall amounts for the entire southwest at “official” locations compared to average.

For next month, I will report on October and give a preview for what is expected this winter. At the time of this writing on October 22, my location and the airport has reported very little rain for the month and temperatures have generally been pleasant.

John Simpson has lived in southern Arizona the past 33 years and Vail for 17 of those years. John has a bachelor’s degree in Atmospheric Science from the University of Missouri and a master’s degree in Atmospheric Physics from the University of Arizona. He loves exploring the outdoors with his family and photographing weather and the beauty of southern Arizona.

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