Roseau weather in September
September in Roseau: sweltering, rainy, with clean air — an excellent time to visit.
#8 of 12 months in Roseau · #293 of 604 destinations to visit in September · comfort 81/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
Roseau climate normals — September
| Daytime high | 29°C / 84°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 27°C / 80°F | |
| Feels like (high) | 34°C / 93°F | |
| Rainfall | 99 mm / 3.9 in | 🌧 rainy |
| Rainy days | 16 days | |
| Humidity | 82% | 💦 very humid |
| Dew point | 24°C / 76°F | |
| Sunshine | 11.1 h/day | |
| Daylight | 12.2 h | |
| Wind | 25 km/h / 16 mph | |
| Air quality (US AQI) | 36 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Roseau in September — FAQ
- Is September a good time to visit Roseau?
- September in Roseau: sweltering, rainy, with clean air — an excellent time to visit. It ranks #8 of 12 months for Roseau on SeasonMap's comfort score (81/100).
- What is the weather like in Roseau in September?
- In September, Roseau averages a daily high of 28.8°C and a low of 26.7°C, with about 99.2 mm of rain over roughly 15.6 rainy days.
- What is the air quality in Roseau in September?
- Roseau has a mean US Air Quality Index of about 36 in September.