Seoul weather in September
September in Seoul: warm, soaked, with very humid — a great time to visit.
#5 of 12 months in Seoul · #367 of 604 destinations to visit in September · comfort 76/100 (tier B)
Updated June 2026 · climate normals from ERA5 reanalysis
Seoul climate normals — September
| Daytime high | 25°C / 78°F | 🌤 warm |
|---|---|---|
| Nighttime low | 18°C / 64°F | |
| Feels like (high) | 27°C / 81°F | |
| Rainfall | 159 mm / 6.2 in | ⛈ soaked |
| Rainy days | 10 days | |
| Humidity | 79% | 💦 very humid |
| Dew point | 18°C / 64°F | |
| Sunshine | 8 h/day | |
| Daylight | 12.4 h | |
| Wind | 13 km/h / 8 mph | |
| Air quality (US AQI) | 73 | 🙂 moderate |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Seoul in September — FAQ
- Is September a good time to visit Seoul?
- September in Seoul: warm, soaked, with very humid — a great time to visit. It ranks #5 of 12 months for Seoul on SeasonMap's comfort score (76/100).
- What is the weather like in Seoul in September?
- In September, Seoul averages a daily high of 25.4°C and a low of 17.6°C, with about 158.5 mm of rain over roughly 9.6 rainy days.
- What is the air quality in Seoul in September?
- Seoul has a mean US Air Quality Index of about 73 in September.