Charleston weather in September
September in Charleston: hot, soaked, with clean air — a good time to visit.
#9 of 12 months in Charleston · #446 of 604 destinations to visit in September · comfort 67/100 (tier C)
Updated June 2026 · climate normals from ERA5 reanalysis
Charleston climate normals — September
| Daytime high | 28°C / 82°F | 🥵 hot |
|---|---|---|
| Nighttime low | 22°C / 72°F | |
| Feels like (high) | 31°C / 88°F | |
| Rainfall | 168 mm / 6.6 in | ⛈ soaked |
| Rainy days | 12 days | |
| Humidity | 78% | 💦 very humid |
| Dew point | 20°C / 68°F | |
| Sunshine | 9.8 h/day | |
| Daylight | 12.4 h | |
| Wind | 18 km/h / 11 mph | |
| Air quality (US AQI) | 46 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Charleston in September — FAQ
- Is September a good time to visit Charleston?
- September in Charleston: hot, soaked, with clean air — a good time to visit. It ranks #9 of 12 months for Charleston on SeasonMap's comfort score (67/100).
- What is the weather like in Charleston in September?
- In September, Charleston averages a daily high of 27.8°C and a low of 22.4°C, with about 168.2 mm of rain over roughly 12.4 rainy days.
- What is the air quality in Charleston in September?
- Charleston has a mean US Air Quality Index of about 46 in September.