Climate averages 1991–2020
San Juan weather
in January.
A hot, fairly dry month: the coolest and the joint 2nd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
January is a hot month in San Juan: daytime highs average 28.0°C and nights cool to about 21.5°C. By daytime temperature it is the coolest month of the year.
Expect about 39 mm of rain on roughly 10 days, which makes January a fairly dry month (the joint 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 11 h 09 min on an average January day.
The nearest other city in this atlas is Bayamón (9 km away). In January its highs average 27.9°C, about as warm as San Juan, with 38 mm of rain.
Among the 7 cities listed in Puerto Rico, San Juan ranks joint 3rd of 7 for the warmest January highs and joint 4th of 7 for the driest January (rainfall, lowest first). The mean January high of those 7 cities is 28.0°C; San Juan is level with that mean.
From January to February, average highs rise by 0.6°C to 28.6°C, and monthly rainfall falls from 39 mm to 29 mm.
The annual picture
January in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
San Juan climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January, selected | 28.0°C21.5°C | 21.5°C | 39 | 10.4 | 11.211 h |
| February | 28.6°C21.3°C | 21.3°C | 29 | 7.7 | 11.512 h |
| March | 29.3°C21.5°C | 21.5°C | 39 | 8.4 | 12.012 h |
| April | 30.0°C22.3°C | 22.3°C | 72 | 11.0 | 12.613 h |
| May | 30.4°C23.4°C | 23.4°C | 112 | 16.1 | 13.013 h |
| June | 31.3°C24.3°C | 24.3°C | 68 | 13.8 | 13.213 h |
| July | 31.5°C24.6°C | 24.6°C | 80 | 16.4 | 13.113 h |
| August | 31.5°C24.7°C | 24.7°C | 95 | 18.7 | 12.813 h |
| September | 31.2°C24.5°C | 24.5°C | 131 | 20.8 | 12.312 h |
| October | 30.4°C24.1°C | 24.1°C | 124 | 20.5 | 11.712 h |
| November | 28.9°C23.2°C | 23.2°C | 112 | 18.2 | 11.311 h |
| December | 28.1°C22.1°C | 22.1°C | 48 | 12.2 | 11.011 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
January in nearby cities
- Bayamón in JanuaryPuerto Rico · 9 kmHigh 27.9°C · Low 21.5°C · 38 mm rain
- Carolina in JanuaryPuerto Rico · 18 kmHigh 27.6°C · Low 21.8°C · 39 mm rain
- Caguas in JanuaryPuerto Rico · 27 kmHigh 27.1°C · Low 21.7°C · 49 mm rain
- Arecibo in JanuaryPuerto Rico · 64 kmHigh 28.3°C · Low 21.5°C · 41 mm rain
- Ponce in JanuaryPuerto Rico · 75 kmHigh 28.0°C · Low 21.8°C · 22 mm rain
- Mayagüez in JanuaryPuerto Rico · 113 kmHigh 28.8°C · Low 22.8°C · 16 mm rain
- Punta Cana in JanuaryDominican Republic · 243 kmHigh 26.0°C · Low 23.7°C · 39 mm rain
- Salvaleón de Higüey in JanuaryDominican Republic · 275 kmHigh 27.0°C · Low 21.6°C · 27 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for San Juan) is explained once on the San Juan year overview and on the Sources, method and limits page.
Carolina lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.