The average temperature in Boise, ID the average temperature is 36.59 degrees in summer, with precipitation around 2.3 mm , Flagstaff, AZ's temperatures reach 34.51 during the hot season, with 9.0 average of rain rate . In winter, however, weather indicators show around -12.89 degrees in Flagstaff, AZ, compared to the -13.87 average degrees reported in Boise, ID. During the winter period, Boise, ID can register 3.0 mm precipitation, while Flagstaff, AZ have an average of 3.0 mm rain level.