In December, Saint Charles typically sees daytime highs of 6.1°C and overnight lows around -3.8°C. Compared to the annual average high of 18.7°C, December runs -12.6°C.
December in Saint Charles averages a daytime high of 6.1°C and an overnight low of -3.8°C.
December runs -12.6°C compared to Saint Charles's annual average high of 18.7°C, ranking #11 of 12 months by warmth.
Plan for daytime highs near 6.1°C and cooler evenings around -3.8°C.