October Weather
During the month of October, weather is generated more from storm activity over the Pacific Ocean than from the subtropical moisture. High pressure systems that bring Indian Summer to the eastern sections of the Nation pass across the Great Basin area to the north, and dry, cold fronts often pass southward across Arizona, drying out and cooling the air.
The average temperature for the month is 74.5 or 19.0 degrees cooler than July. Daytime high temperatures usually begin the month at 94 but cool off to 82 by Halloween. Nighttime low temperatures drop from 67 to 54. These are the largest changes in normal high and low temperatures that occur during any month of the year. Record temperature extremes for the month range from 107 in 1980 to 34 in 1971. October does average one day each year with at least 100 or higher. The latest in the season that a temperature of 100 or higher has ever occurred was October 20, 1921.
Rainfall amounts to only 0.65 inches on the average. Rain falls more evenly during the 24 hours in contrast to the summer months when it is concentrated during the night.
The most rain that ever fell since records began was 4.40 inches in 1972. There is usually one thunderstorm day during the month.
The month averages four cloudy days. It averages 88 percent of possible sunshine and has never had less than 65 percent.
On the whole, October is a magnificent month with enough of the summer warmth to make outdoor living the most enjoyable of the year and yet with enough coolness to make it invigorating.