The charts below illustrate the mean annual cycle of precipitation for six observing stations in interior or northern Alaska; the first shows the mean total precipitation by month, and the second shows the mean frequency of measurable (0.01 inches or more) precipitation by month. The amount of precipitation peaks in August for all six stations, and August is also the time of peak frequency of precipitation, except for Barrow where precipitation frequency peaks in October. It is interesting to note that Fairbanks shows a sharper decline in precipitation amount and precipitation frequency from August to September than the rest of the stations, indicating a marked change to drier conditions in September. The average daily precipitation amount peaks on about July 30 in Fairbanks, but the peak occurs in mid-August for the other locations.
Looking more closely at Fairbanks, the next chart shows the mean daily distribution of precipitation frequency and amount around the year. The seasonal peaks are quite pronounced, with minimum precipitation falling in April and the maximum occurring only three and a half months later. The secondary peak in precipitation frequency in October is interesting and may reflect a period of disturbed weather that tends to accompany the precipitous mid-autumn decline in temperature.