Kauai weather in September
September in Kauai: warm, a little rain, with clean air — one of the best months to visit.
#2 of 12 months in Kauai · #66 of 604 destinations to visit in September · comfort 90/100 (tier S)
Updated June 2026 · climate normals from ERA5 reanalysis
Kauai climate normals — September
| Daytime high | 26°C / 79°F | 🌤 warm |
|---|---|---|
| Nighttime low | 21°C / 70°F | |
| Feels like (high) | 28°C / 82°F | |
| Rainfall | 32 mm / 1.3 in | 🌦 some rain |
| Rainy days | 14 days | |
| Humidity | 74% | 💧 humid |
| Dew point | 18°C / 64°F | |
| Sunshine | 11.2 h/day | |
| Daylight | 12.3 h | |
| Wind | 15 km/h / 10 mph | |
| Air quality (US AQI) | 22 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Where is Kauai?
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Kauai in September — FAQ
- Is September a good time to visit Kauai?
- September in Kauai: warm, a little rain, with clean air — one of the best months to visit. It ranks #2 of 12 months for Kauai on SeasonMap's comfort score (90/100).
- What is the weather like in Kauai in September?
- In September, Kauai averages a daily high of 26.1°C and a low of 21.1°C, with about 31.8 mm of rain over roughly 14 rainy days.
- What is the air quality in Kauai in September?
- Kauai has a mean US Air Quality Index of about 22 in September.