A single powerful storm pushed September's total rainfall over the monthly average for Prescott.
The storm occurred after the end of the annual monsoon. The Sept. 22 thunderstorm dumped 1.79 inches of rain on the National Weather Service measuring site on the northeast side of Prescott, more than the long-term average for the entire month.
The total September rainfall at the Sundog site was 1.92 inches, which is 112 percent of the 109-year average of 1.71 inches.
Instead of originating from the south as it commonly occurs during the monsoon, the Sept. 22 storm was associated with an unusually strong Pacific low-pressure system. The widespread system prompted a tornado warning in the Bumble Bee area of southern Yavapai County, and produced
golf-ball-sized hail in Castle Hot Springs in extreme southern Yavapai County.
September is only the second month to have above-average precipitation since last October. The other above-average month was July.