Originally Published: October 3, 2011 9:55 p.m.
It was a relatively hot and dry summer, but get ready for a wet and cold week.
Western Yavapai County including Prescott received below-normal precipitation during the 2011 monsoon, despite a strong showing toward the end.
Prescott saw only about half its average monsoon rains despite getting 1.82 inches of rain in September. That month was 107 percent of the 113-year average.
A local warming trend continued in September despite the good rains. The average high temperature was 3.1 degrees above the 113-year average, while the average low temperature was 6 degrees above average.
The monsoon officially ended Friday, and ironically a series of storms forecasted for this week could make October wetter than some monsoon months this year.
The temperature is expected to drop significantly this week too, with a forecasted high of 55 degrees by Thursday.
The National Weather Service says Prescott got only 52 percent of its average monsoon precipitation during the official monsoon dates of June 15 through Sept. 30, with 4.17 inches compared to the average 7.96 inches.
The Weather Service produced a chart showing that several other communities in Yavapai County also recorded poor monsoon precipitation numbers, with Bagdad at 42 percent of average (2.25 inches), Seligman at 78 percent of average (4.37 inches), and Castle Hot Springs at only 20 percent of average (1 inch).
At the same time, the Verde Valley communities of eastern Yavapai County registered much stronger numbers with Camp Verde at 102 percent of average (5.99 inches), Jerome at 96 percent of average (7.07 inches), and Cottonwood/Clarkdale at 97 percent (5.2 inches).
Communities in the White Mountains and Flagstaff area also fared much better than western Yavapai County, peaking at 123 percent of average at Sunset Crater National Monument (9.78 inches) and 122 percent of average at Springerville (9.05 inches).
August was the worst surprise for Prescott, producing only 17 percent of the average 3.22 inches that normally makes it the wettest month of the year. The dry weather led to a dozen daily heat records in the Prescott area.
The region experienced an unusually high number of strong low-pressure systems moving in from the West Coast, pushing out the moist southerly flows common during the monsoon.
June was bone dry so it tied the record for the driest June in Prescott. July's rains were 62.5 percent of average.
Nationally it was the second-warmest summer on record, according to the National Climatic Data Center.
Rain, cold this week
The local weather story is changing at least briefly this week as a series of storms moves through northern Arizona.
Rain is likely to fall in Prescott today through Thursday as the Weather Service has forecasted a 50-percent chance today, a 50-percent chance Wednesday night and a 70-percent chance Thursday when a strong cold front moves in.
Temperatures will drop noticeably, with a forecast high of 69 degrees today, 66 Wednesday, 55 Thursday and 56 Friday. The low could hit 36 degrees Thursday and 39 Friday in Prescott.
Snow could fall in areas as low as 7,000 feet in northern Arizona, with freezing probable for the high country Friday and Saturday mornings.
Strong winds will arrive in front of the series of storm systems, with gusts as strong as 37 mph in Prescott today. Gusts could reach 36 mph Wednesday night just ahead of the strong Pacific storm.
La Niña on way
The Weather Service is predicting the possibility for more than an inch of rain in the higher elevations of Yavapai County this week.
The long-term forecast is calling for above-average chances for a dry winter in the Southwest, however, because La Niña is settling in.
While La Niña typically occurs every three to five years, the most recent event was just a year ago. La Niña is associated with cooler than normal temperatures in the equatorial Pacific Ocean.