In May, Boise typically sees daytime highs of 20.6°C and overnight lows around 5.3°C. Compared to the annual average high of 15.8°C, May runs +4.7°C.
May in Boise averages a daytime high of 20.6°C and an overnight low of 5.3°C.
May runs +4.7°C compared to Boise's annual average high of 15.8°C, ranking #5 of 12 months by warmth.
Plan for daytime highs near 20.6°C and cooler evenings around 5.3°C.