In December, Sarnia typically sees daytime highs of 1.0°C and overnight lows around -5.8°C. Compared to the annual average high of 13.3°C, December runs -12.4°C.
December in Sarnia averages a daytime high of 1.0°C and an overnight low of -5.8°C.
December runs -12.4°C compared to Sarnia's annual average high of 13.3°C, ranking #10 of 12 months by warmth.
Plan for daytime highs near 1.0°C and cooler evenings around -5.8°C.