December Weather

By December, freezing temperatures in the valley are rather common, and freezing temperatures can be expected somewhere in the area on fifteen to twenty days of the month.

High daytime temperatures on the first of the month are about 69 and taper off slowly to 65 by the end of the month. Nighttime temperatures drop from 44 to 40. The highest temperature ever recorded was 87 on the 10th in 1950, and the lowest was 22 on the 31st in 1900 and on the 26th in 1911.

Total rainfall for the month averages 1.00 inch and is the highest of any month of the year. There are usually four days with 0.01 inches or more. Pacific storm systems move a little farther south, bringing more moisture to replenish the water supply with snows in the mountains. The most rain recorded was 3.98 inches in 1967, and the least was none in 1900, 1901, 1917, 1958, 1973, and 1981.

A trace of snow has been reported on eight December days since 1896; 0.1 inches fell on the 11th in 1985, and 0.2 inches on both the 21st and 22nd in 1990.

Sunshine now averages 77 percent with nine cloudy days. There was 98 percent of possible observed in 1958 and as little as 47 percent in 1914.