San Juan weather in December
December in San Juan: hot, a little rain, with clean air — a great time to visit.
#4 of 12 months in San Juan · #206 of 604 destinations to visit in December · comfort 77/100 (tier B)
Updated June 2026 · climate normals from ERA5 reanalysis
San Juan climate normals — December
| Daytime high | 29°C / 83°F | 🥵 hot |
|---|---|---|
| Nighttime low | 23°C / 73°F | |
| Feels like (high) | 31°C / 88°F | |
| Rainfall | 38 mm / 1.5 in | 🌦 some rain |
| Rainy days | 12 days | |
| Humidity | 80% | 💦 very humid |
| Dew point | 21°C / 70°F | |
| Sunshine | 10.2 h/day | |
| Daylight | 11 h | |
| Wind | 19 km/h / 12 mph | |
| Air quality (US AQI) | 32 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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San Juan in December — FAQ
- Is December a good time to visit San Juan?
- December in San Juan: hot, a little rain, with clean air — a great time to visit. It ranks #4 of 12 months for San Juan on SeasonMap's comfort score (77/100).
- What is the weather like in San Juan in December?
- In December, San Juan averages a daily high of 28.6°C and a low of 22.5°C, with about 37.7 mm of rain over roughly 11.8 rainy days.
- What is the air quality in San Juan in December?
- San Juan has a mean US Air Quality Index of about 32 in December.