Last updated: August 27, 2025
In San Antonio, Mexico, the average temperature in December hovers around 18°C (64°F). Expect a minimum of 4°C (39°F) and a maximum of 32°C (89°F) during this time. With an average precipitation of 37 mm (1.5 in) spread across 6 days, the atmosphere can feel quite humid at 91%. Be prepared for a mix of warmth and moisture!
In December in San Antonio, the average temperature is 18°C (64°F). Maximums can reach 32°C (89°F), and minimums can be as low as 4°C (39°F). This makes it an ideal time for travelers seeking pleasant weather and a variety of outdoor activities.
In San Antonio in December, the precipitation amount is 37 mm (1.5 in) over the course of 6 days.
In San Antonio in December humidity is 91%. With an average temperature of 18°C (64°F), this humidity feels like a thick blanket enveloping you, making any outdoor activities somewhat draining and requiring frequent hydration to stay comfortable while exploring.
In San Antonio in December, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in San Antonio.
UV Risk Categories
Weather in San Antonio varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in San Antonio, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 17°C (63°F) | 57 mm (2.3 inches) | 88% | high |
| February Weather | 19°C (66°F) | 51 mm (2.0 inches) | 86% | very high |
| March Weather | 21°C (71°F) | 66 mm (2.6 inches) | 83% | extreme |
| April Weather | 24°C (76°F) | 83 mm (3.3 inches) | 80% | extreme |
| May Weather | 26°C (80°F) | 147 mm (5.8 inches) | 82% | extreme |
| June Weather | 26°C (79°F) | 195 mm (7.7 inches) | 79% | extreme |
| July Weather | 26°C (79°F) | 138 mm (5.4 inches) | 72% | extreme |
| August Weather | 27°C (80°F) | 121 mm (4.8 inches) | 74% | extreme |
| September Weather | 26°C (78°F) | 226 mm (8.9 inches) | 84% | extreme |
| October Weather | 23°C (74°F) | 275 mm (10.8 inches) | 92% | extreme |
| November Weather | 20°C (68°F) | 73 mm (2.9 inches) | 91% | very high |
| December Weather | 18°C (64°F) | 37 mm (1.5 inches) | 91% | high |