January in San Marcos averages a daily high of 17.4°C with nights around 3.9°C. Expect roughly 6.6 wet days totalling 60.2mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit San Marcos is February–April.
Based on SAN MARCOS, TX US (0.8km), 1995–2024. 29 years of January data.