Last updated: August 27, 2025
In December, the average temperature in San Juan, Mexico hovers around 18°C (64°F), offering a pleasant climate. However, temperatures can range from a cool 4°C (40°F) to a warm 31°C (88°F). Expect minimal rain, with 24 mm (0.9 in) of precipitation spread over just 2 days, and enjoy a comfortably high average humidity of 78%.
In December in San Juan, the average temperature is 18°C (64°F). Maximum temperatures can reach 31°C (88°F), while minimum temperatures can drop to as low as 4°C (40°F). This variability makes San Juan a versatile destination, perfect for travelers looking to enjoy both warm days and cool evenings.
In San Juan in December, the total precipitation amount is 24 mm (0.9 in) over a period of 2 days.
In San Juan in December, humidity is 78%. With an average temperature of 18°C (64°F), this humidity feels like a warm, thick blanket wrapping around you, making traveling feel a bit sticky and sluggish, yet the coolness of the air tempers the intensity, inviting you to explore at a leisurely pace.
In San Juan in December, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in San Juan, you can refer to this Hourly UV Index in San Juan.
UV Risk Categories
Weather in San Juan varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in San Juan, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 17°C (63°F) | 11 mm (0.4 inches) | 74% | high |
| February Weather | 18°C (65°F) | 37 mm (1.5 inches) | 66% | very high |
| March Weather | 20°C (68°F) | 2 mm (0.1 inches) | 61% | extreme |
| April Weather | 22°C (72°F) | 1 mm (0.0 inches) | 56% | extreme |
| May Weather | 24°C (76°F) | 2 mm (0.1 inches) | 61% | extreme |
| June Weather | 26°C (78°F) | 73 mm (2.9 inches) | 73% | extreme |
| July Weather | 24°C (76°F) | 217 mm (8.6 inches) | 82% | extreme |
| August Weather | 25°C (76°F) | 255 mm (10.0 inches) | 83% | extreme |
| September Weather | 24°C (75°F) | 166 mm (6.5 inches) | 83% | extreme |
| October Weather | 23°C (74°F) | 68 mm (2.7 inches) | 78% | extreme |
| November Weather | 21°C (69°F) | 13 mm (0.5 inches) | 77% | very high |
| December Weather | 18°C (64°F) | 24 mm (0.9 inches) | 78% | high |