Juneau averages over 50 inches (1,270 mm) of precipitation a year, while some other areas in southeast Alaska receive as much as 275 inches (6,980 mm).Average monthly precipitation generally peaks in September or October, and is lowest in May and June.nland, often less than 10 inches (254 mm) falls a year and on the North Slope as little as 4 inches (100 mm) of rainfall equivalent and 30 inches (0.76 m) of snow is typical, but what snow falls during the winter tends to stay throughout the season.