In December, Boulder typically sees daytime highs of 3.9°C and overnight lows around -8.7°C. Compared to the annual average high of 13.6°C, December runs -9.7°C.
December in Boulder averages a daytime high of 3.9°C and an overnight low of -8.7°C.
December runs -9.7°C compared to Boulder's annual average high of 13.6°C, ranking #11 of 12 months by warmth.
Plan for daytime highs near 3.9°C and cooler evenings around -8.7°C.