Climate averages 1991–2020
Bayamón weather
in September.
A hot, wet month: the 4th warmest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in Bayamón: daytime highs average 31.1°C and nights cool to about 24.6°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 122 mm of rain on roughly 20 days, which makes September a wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 12 h 15 min on an average September day.
The nearest other city in this atlas is San Juan (9 km away). In September its highs average 31.2°C, about as warm as Bayamón, with 131 mm of rain.
Among the 7 cities listed in Puerto Rico, Bayamón ranks 3rd of 7 for the warmest September highs and 2nd of 7 for the driest September (rainfall, lowest first). The mean September high of those 7 cities is 30.7°C; Bayamón is 0.4°C warmer than that mean.
From September to October, average highs fall by 0.8°C to 30.3°C, and monthly rainfall falls from 122 mm to 113 mm.
The annual picture
September 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
Bayamón climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 27.9°C21.5°C | 21.5°C | 38 | 9.9 | 11.211 h |
| February | 28.5°C21.4°C | 21.4°C | 28 | 7.7 | 11.512 h |
| March | 29.3°C21.5°C | 21.5°C | 40 | 8.2 | 12.012 h |
| April | 29.9°C22.4°C | 22.4°C | 70 | 10.7 | 12.513 h |
| May | 30.4°C23.5°C | 23.5°C | 106 | 15.6 | 13.013 h |
| June | 31.3°C24.4°C | 24.4°C | 60 | 12.8 | 13.213 h |
| July | 31.5°C24.6°C | 24.6°C | 66 | 15.3 | 13.113 h |
| August | 31.6°C24.8°C | 24.8°C | 79 | 17.4 | 12.713 h |
| September, selected | 31.1°C24.6°C | 24.6°C | 122 | 20.2 | 12.312 h |
| October | 30.3°C24.1°C | 24.1°C | 113 | 19.8 | 11.712 h |
| November | 28.8°C23.2°C | 23.2°C | 102 | 17.4 | 11.311 h |
| December | 28.1°C22.2°C | 22.2°C | 45 | 12.0 | 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
September in nearby cities
- San Juan in SeptemberPuerto Rico · 9 kmHigh 31.2°C · Low 24.5°C · 131 mm rain
- Carolina in SeptemberPuerto Rico · 21 kmHigh 30.9°C · Low 24.6°C · 131 mm rain
- Caguas in SeptemberPuerto Rico · 22 kmHigh 30.1°C · Low 24.6°C · 168 mm rain
- Arecibo in SeptemberPuerto Rico · 60 kmHigh 31.2°C · Low 24.4°C · 154 mm rain
- Ponce in SeptemberPuerto Rico · 66 kmHigh 29.7°C · Low 24.5°C · 124 mm rain
- Mayagüez in SeptemberPuerto Rico · 106 kmHigh 30.6°C · Low 25.6°C · 98 mm rain
- Punta Cana in SeptemberDominican Republic · 238 kmHigh 28.9°C · Low 26.0°C · 121 mm rain
- Salvaleón de Higüey in SeptemberDominican Republic · 270 kmHigh 30.2°C · Low 24.2°C · 107 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 Bayamón) is explained once on the Bayamón year overview and on the Sources, method and limits page.