San Juan, Puerto Rico weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Poor
Best time to visit: December – April
What is the weather like in San Juan, Puerto Rico in September?
In September, San Juan, Puerto Rico is hot: daytime highs average 31 °C, and even at night it stays warm at around 25 °C. The sea averages 29.1 °C – almost as warm as a bath. The sun shines for around 7 hours a day. It is the rainy season: rain falls on about 21 days, totalling 131 mm. On about 26 days the thermometer climbs to 30 °C or more. The air is often humid and muggy. All in all, September is not an ideal month for a holiday in San Juan, Puerto Rico.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 39 | 38 | 42 |
| Day | 32° | 31° | 31° |
| Night | 25° | 25° | 24° |
| Sea | 29° | 29° | 29° |
| Sun | 8 h | 7 h | 7 h |
| Rain days | 18 | 21 | 20 |
More details for September
- Daylight
- 12 h 16 min06:12 – 18:28
- UV index
- 12 · extremeclear sky, noon (estimate)All months
- Muggy days
- 30 daysdew point 18 °C or more
- Wind
- 17 km/haverage daily peak
- Cloud cover
- 62 %on average
- Hot days
- 26 days30 °C or more
- Time zone
- UTC−4America/Puerto_Rico
How the score comes together
- Temperatureweight 50 %46 %
- Sunshineweight 20 %73 %
- Few rainy daysweight 30 %0 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in September
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Water bottle – drink plenty
- Insect repellent
- Rain jacket or umbrella
San Juan, Puerto Rico in September: quick answers
Is San Juan, Puerto Rico hot in September?
Yes. In September, San Juan, Puerto Rico is hot: daytime highs average 31 °C and nights stay around 25 °C. On about 26 days the thermometer climbs to 30 °C or more.
Can you swim in San Juan, Puerto Rico in September?
Yes. In September the sea averages 29.1 °C – almost as warm as a bath.
Does it rain much in San Juan, Puerto Rico in September?
It rains often – on about 21 days, adding up to 131 mm.
San Juan, Puerto Rico month by month
The whole year in San Juan, Puerto RicoAll destinations: Puerto RicoCaribbean weather in SeptemberWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0)