Last updated: June 24, 2025
In December, the average temperature in San Marcos, United States is a comfortable 14°C (57°F). You'll experience a pleasant range, with minimums dipping to 3°C (39°F) and maximums reaching up to 28°C (83°F). However, be prepared for some rain, as precipitation amounts can hit 70 mm (2.7 in) over about 6 days. Don't forget that the average humidity hovers around a cozy 74%, making it a perfect time to enjoy the vibrant atmosphere of the season!
In December in San Marcos, the average temperature is 14°C (57°F). Maximums can reach 28°C (83°F), and minimums can be as low as 3°C (39°F). This mild climate makes San Marcos an ideal destination for travelers looking to explore comfortably.
In San Marcos in December, the total precipitation amount is 70 mm (2.7 in), occurring over the span of 6 days.
In San Marcos in December, humidity is 74%. With an average temperature of 14°C (57°F), this humidity feels like a warm, damp blanket wrapping around you, making it slightly uncomfortable for traveling, as you may find yourself quickly sweating and in need of frequent breaks to cool down.
In San Marcos in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in San Marcos for better planning.
UV Risk Categories
Weather in San Marcos varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in San Marcos, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 13°C (56°F) | 70 mm (2.8 inches) | 72% | moderate |
| February Weather | 13°C (56°F) | 78 mm (3.1 inches) | 77% | high |
| March Weather | 14°C (58°F) | 68 mm (2.7 inches) | 67% | very high |
| April Weather | 16°C (62°F) | 32 mm (1.3 inches) | 56% | very high |
| May Weather | 17°C (63°F) | 24 mm (0.9 inches) | 46% | extreme |
| June Weather | 20°C (68°F) | 3 mm (0.1 inches) | 48% | extreme |
| July Weather | 23°C (73°F) | 4 mm (0.2 inches) | 46% | extreme |
| August Weather | 24°C (75°F) | 1 mm (0.1 inches) | 42% | very high |
| September Weather | 23°C (73°F) | 5 mm (0.2 inches) | 52% | very high |
| October Weather | 20°C (69°F) | 12 mm (0.5 inches) | 58% | high |
| November Weather | 17°C (63°F) | 34 mm (1.4 inches) | 66% | moderate |
| December Weather | 14°C (57°F) | 70 mm (2.7 inches) | 74% | moderate |