Last updated: August 27, 2025
In December, the average temperature in San Juan, Peru hovers around 12°C (54°F), offering a mild climate. Temperatures can fluctuate from a chilly 3°C (38°F) at their lowest to a pleasant 21°C (70°F) at their peak. Expect considerable precipitation, totaling 413 mm (16.2 in) over 26 days, contributing to the region's lush environment. The air is typically humid, with an average humidity level of 82%, giving you plenty of reasons to embrace this vibrant season.
In December in San Juan, the average temperature is 12°C (54°F), with maximums reaching up to 21°C (70°F) and minimums dipping as low as 3°C (38°F). This mild climate makes it an ideal time for travelers to explore the area's sights and enjoy outdoor activities.
In San Juan in December, the total precipitation amount is 413 mm (16.2 in) over the course of 26 days.
In San Juan in December humidity is 82%. With an average temperature of 12°C (54°F), this humidity feels like a heavy blanket wrapping around you, making every step feel sluggish and sweat-inducing, which can be quite uncomfortable for traveling.
In San Juan in December, the maximum UV index is 16, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, making it crucial to take protective measures. For detailed information, you can refer to the 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 | 12°C (54°F) | 304 mm (12.0 inches) | 83% | extreme |
| February Weather | 12°C (54°F) | 392 mm (15.4 inches) | 81% | extreme |
| March Weather | 12°C (53°F) | 599 mm (23.6 inches) | 88% | extreme |
| April Weather | 12°C (54°F) | 348 mm (13.7 inches) | 85% | extreme |
| May Weather | 12°C (54°F) | 188 mm (7.4 inches) | 78% | extreme |
| June Weather | 12°C (54°F) | 70 mm (2.8 inches) | 62% | extreme |
| July Weather | 12°C (54°F) | 43 mm (1.7 inches) | 44% | extreme |
| August Weather | 12°C (55°F) | 47 mm (1.9 inches) | 38% | extreme |
| September Weather | 12°C (54°F) | 154 mm (6.1 inches) | 42% | extreme |
| October Weather | 12°C (54°F) | 299 mm (11.8 inches) | 58% | extreme |
| November Weather | 12°C (54°F) | 290 mm (11.4 inches) | 69% | extreme |
| December Weather | 12°C (54°F) | 413 mm (16.2 inches) | 82% | extreme |