With the end of September marking the end of the water year, it’s a good time to look back on this year’s summer rainfall, and compare it to previous years. While the summer monsoon season “officially” runs from June 15 to September 30, it’s not like rain in May and early June doesn’t matter. So, the graph above compares cumulative precipitation over the period from May 1 to late October. And, although well into August it looked like 2025 might be a total dud, or what some call a “non-soon,” abundant rainfall over the last six weeks turned things around. As measured by a Campbell Scientific ClimaVue all-in-one weather station located in the Forestdale neighborhood of southeast Flagstaff, the official precipitation total from May 1 to today (October 1) is a very respectable 197.4 mm, or 7.8″. Compared to the previous 5 y, it’s almost three times as much as the ultra-dry summer of 2020, but about 40% less than the epically-wet summer of 2021.
Fun fact: The final September rain in Flagstaff brought the first autumn snow to the highest summits of the San Francisco peaks, although it melted away by mid-day.