Climate averages 1991–2020
San Juan weather
in May.
A hot, wet month: the joint 5th warmest and the joint 9th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
May is a hot month in San Juan: daytime highs average 30.4°C and nights cool to about 23.4°C. By daytime temperature it is the joint 5th warmest of the 12 months.
Expect about 112 mm of rain on roughly 16 days, which makes May a wet month (the joint 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 59 min on an average May day.
The nearest other city in this atlas is Bayamón (9 km away). In May its highs average 30.4°C, about as warm as San Juan, with 106 mm of rain.
Among the 7 cities listed in Puerto Rico, San Juan ranks joint 1st of 7 for the warmest May highs and joint 4th of 7 for the driest May (rainfall, lowest first). The mean May high of those 7 cities is 29.9°C; San Juan is 0.5°C warmer than that mean.
From May to June, average highs rise by 0.9°C to 31.3°C, and monthly rainfall falls from 112 mm to 68 mm.
The annual picture
May 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, selected | 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
May in nearby cities
- Bayamón in MayPuerto Rico · 9 kmHigh 30.4°C · Low 23.5°C · 106 mm rain
- Carolina in MayPuerto Rico · 18 kmHigh 30.0°C · Low 23.6°C · 112 mm rain
- Caguas in MayPuerto Rico · 27 kmHigh 29.3°C · Low 23.5°C · 141 mm rain
- Arecibo in MayPuerto Rico · 64 kmHigh 30.4°C · Low 23.3°C · 165 mm rain
- Ponce in MayPuerto Rico · 75 kmHigh 29.0°C · Low 23.5°C · 86 mm rain
- Mayagüez in MayPuerto Rico · 113 kmHigh 29.8°C · Low 24.5°C · 70 mm rain
- Punta Cana in MayDominican Republic · 243 kmHigh 27.7°C · Low 24.9°C · 100 mm rain
- Salvaleón de Higüey in MayDominican Republic · 275 kmHigh 29.3°C · Low 23.1°C · 98 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.