In December, San Marcos typically sees daytime highs of 17.7°C and overnight lows around 4.7°C. Compared to the annual average high of 26.3°C, December runs -8.6°C.
December in San Marcos averages a daytime high of 17.7°C and an overnight low of 4.7°C.
December runs -8.6°C compared to San Marcos's annual average high of 26.3°C, ranking #11 of 12 months by warmth.
Plan for daytime highs near 17.7°C and cooler evenings around 4.7°C.