In December, Napa typically sees daytime highs of 12.8°C and overnight lows around 2.6°C. Compared to the annual average high of 21.5°C, December runs -8.7°C.
December in Napa averages a daytime high of 12.8°C and an overnight low of 2.6°C.
December runs -8.7°C compared to Napa's annual average high of 21.5°C, ranking #11 of 12 months by warmth.
Plan for daytime highs near 12.8°C and cooler evenings around 2.6°C.