Climate averages 1991–2020
San Juan weather
in August.
A hot, wet month: one of the warmest and the 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a hot month in San Juan: daytime highs average 31.5°C and nights cool to about 24.7°C. By daytime temperature it is one of the warmest months of the year.
Expect about 95 mm of rain on roughly 19 days, which makes August a wet month (the 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 45 min on an average August day.
The nearest other city in this atlas is Bayamón (9 km away). In August its highs average 31.6°C, about as warm as San Juan, with 79 mm of rain.
Among the 7 cities listed in Puerto Rico, San Juan ranks 3rd of 7 for the warmest August highs and joint 4th of 7 for the driest August (rainfall, lowest first). The mean August high of those 7 cities is 31.1°C; San Juan is 0.4°C warmer than that mean.
From August to September, average highs fall by 0.4°C to 31.2°C, and monthly rainfall rises from 95 mm to 131 mm.
The annual picture
August 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 | 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, selected | 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
August in nearby cities
- Bayamón in AugustPuerto Rico · 9 kmHigh 31.6°C · Low 24.8°C · 79 mm rain
- Carolina in AugustPuerto Rico · 18 kmHigh 31.1°C · Low 24.9°C · 95 mm rain
- Caguas in AugustPuerto Rico · 27 kmHigh 30.3°C · Low 24.8°C · 127 mm rain
- Arecibo in AugustPuerto Rico · 64 kmHigh 31.7°C · Low 24.7°C · 101 mm rain
- Ponce in AugustPuerto Rico · 75 kmHigh 30.5°C · Low 24.8°C · 77 mm rain
- Mayagüez in AugustPuerto Rico · 113 kmHigh 31.3°C · Low 25.8°C · 67 mm rain
- Punta Cana in AugustDominican Republic · 243 kmHigh 28.9°C · Low 26.1°C · 105 mm rain
- Salvaleón de Higüey in AugustDominican Republic · 275 kmHigh 30.3°C · Low 24.5°C · 88 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.