In May, St. Catharines typically sees daytime highs of 17.9°C and overnight lows around 7.8°C. Compared to the annual average high of 12.9°C, May runs +5.1°C.
May in St. Catharines averages a daytime high of 17.9°C and an overnight low of 7.8°C.
May runs +5.1°C compared to St. Catharines's annual average high of 12.9°C, ranking #5 of 12 months by warmth.
Plan for daytime highs near 17.9°C and cooler evenings around 7.8°C.