In December, Seattle typically sees daytime highs of 7.9°C and overnight lows around 3.0°C. Compared to the annual average high of 15.2°C, December runs -7.3°C.
December in Seattle averages a daytime high of 7.9°C and an overnight low of 3.0°C.
December runs -7.3°C compared to Seattle's annual average high of 15.2°C, ranking #11 of 12 months by warmth.
Plan for daytime highs near 7.9°C and cooler evenings around 3.0°C.