In May, Great Falls typically sees daytime highs of 18.6°C and overnight lows around 3.8°C. Compared to the annual average high of 13.8°C, May runs +4.9°C.
May in Great Falls averages a daytime high of 18.6°C and an overnight low of 3.8°C.
May runs +4.9°C compared to Great Falls's annual average high of 13.8°C, ranking #5 of 12 months by warmth.
Plan for daytime highs near 18.6°C and cooler evenings around 3.8°C.