In December, Longmont typically sees daytime highs of 7.9°C and overnight lows around -6.8°C. Compared to the annual average high of 18.2°C, December runs -10.3°C.
December in Longmont averages a daytime high of 7.9°C and an overnight low of -6.8°C.
December runs -10.3°C compared to Longmont's annual average high of 18.2°C, ranking #11 of 12 months by warmth.
Plan for daytime highs near 7.9°C and cooler evenings around -6.8°C.