In December, Ontario typically sees daytime highs of 16.9°C and overnight lows around 3.9°C. Compared to the annual average high of 23.1°C, December runs -6.3°C.
December in Ontario averages a daytime high of 16.9°C and an overnight low of 3.9°C.
December runs -6.3°C compared to Ontario's annual average high of 23.1°C, ranking #11 of 12 months by warmth.
Plan for daytime highs near 16.9°C and cooler evenings around 3.9°C.