The Phoenix area generally experiences its coldest weather in January, yet, daytime temperatures still average in the middle sixties. The normal daily maximum is 65.9, and the normal daily minimum 41.2 and the normal mean monthly temperature is 53.6.
The warmest January occurred in 1986 when the mean monthly temperature was 61.4; the coldest was in 1937 with a mean temperature of only 43.2. The highest temperature ever recorded in any January was 88 on the 19th in 1971. The lowest January temperature (and the all-time low for Phoenix) was 16 on January 7, 1913. The warmest night occurred on the 27th in 1988 when the temperature fell no lower than 61. The record cold day for January and for any winter month was January 6, 1913, when the high, low, and mean temperatures were 39, 17, and 28, respectively.
The relative humidity for the month averages about the same as that for December. The low value in the afternoon averages around 33 percent.
The mean hourly surface wind speed is around 5.3 m.p.h., and the prevailing direction is from the east. The peak gust was 60 m.p.h. from the west on January 27, 1983.
Precipitation during the month normally totals 0.67 inches, but it has ranged from 5.22 in 1993 to none in 1912, 1924, and 1972. The greatest amount of precipitation in 24 hours was 1.84 inches which occurred on January 10-11, 1993. There are normally four days with 0.01 inches or more, but January 1993 had fourteen such days.
Snow can occur in January, but it is unusual. Snow in amounts of up to 1 inch has been reported at the official observing station on seven January days since 1896. The heaviest falls of just 1 inch fell in 1933 and 1937. On January 20-21, 1937, amounts up to 4 inches fell in parts of the city and some remained on the ground in shaded areas until the 23rd and 24th.
The mean monthly percentage of possible sunshine is 78 percent. The greatest amount ever recorded was 100 percent in 1924, and the least was 54 percent in 1935.
There are normally 14 clear days, 7 partly cloudy days and 10 cloudy days in the month. The greatest number of clear days was 27 in 1924 and 1925, while the greatest number of cloudy days was 22 in 1957.