Originally Published: October 1, 2009 10:46 p.m.
Prescott saw its 10th-driest monsoon season on record this year, and so far it's also the eighth-driest calendar year on record.
Prescott's period of record dates back to 1898.
Other northern Arizona communities set even worse monsoon records: Bellemont (driest on record), Flagstaff and Winslow (second-driest), Bagdad (fourth), Page (sixth) and Seligman (eighth). Despite a record single-day rainfall of 2.5 inches for Sept. 10 that produced flash flooding, Sedona still registered its 12th-driest monsoon season.
After an unusually wet May and cool June, the monsoon started out early (the last week of June) with a lot of promise. But it quickly petered out to below-average rain and stayed that way for all of July through September.
The official National Weather Service monsoon time period of June 15 through Sept. 30 produced 4.34 inches of rain in Prescott, and registered 8.48 inches for January through September.
Residents can only hope that El Niño helps bring extra precipitation this winter. That tends to happen during strong El Niño winters, but so far this one has been weak to moderate, said Dave Vonderheide, a meteorologist at the National Weather Service office in Flagstaff.
Prescott hasn't seen any rain since Sept. 6.
On the bright side, a cold pressure system moving in from the Great Basin and rich subtropical moisture could bring measurable rain to Prescott Saturday night through early Sunday.
The subtropical moisture is coming from what is now Tropical Storm Olaf developing southwest of the Baja.
"It's pushing it right up into Arizona on Saturday," Vonderheide said.
This area could see about a quarter-inch of steady, slow rain, Vonderheide said. Southern Arizona and northern Mexico will get even more.
As of late Thursday, the Weather Service was forecasting a 40 percent chance of rain Saturday night and 30 percent chance Sunday.
Temperatures will remain cool in comparison to unusually hot days earlier this week and last week, with forecast highs in the 70s and lows in the 40s.
Several northern Arizona communities set record highs last weekend despite cool nighttime temperatures. The Weather Service office at Bellemont saw a temperature swing of 53 degrees in about six hours.
The three monsoon months of July-September produced above-average highs and above-average low temperatures in Prescott. June's average high temperature was below average, but its average low temperature was above average.
Monthly monsoon precipitation compared to the 111-year average for Prescott was:
June: 0.11 inches this year versus the average of 0.39 inches (28 percent of average).
July: 2.12 inches versus the average of 2.9 inches (73 percent).
August: 1.29 inches versus the average of 3.24 inches (40 percent).
September: 1.36 inches versus 1.71 inches (40 percent).