Seoul Weather in September
In September, Seoul averages a high of 26°C (79°F) and a low of 17°C (63°F), from 48 years of daily records (1971–2026).
26°C
Average high
79°F
17°C
Average low
63°F
36°C
Record high
97°F · September 7, 1975
6°C
Record low
43°F · September 27, 1987
What September Is Like in Seoul
- September 2025 was the warmest September in 48 years of records, 1.9°C (3.4°F) above the long-run average.
- The September heat record, 36°C (97°F) on September 7, 1975, has stood for 51 years.
- September in Seoul has become 1.5°C (2.7°F) warmer on average: the 2011–2025 average against 1970–1989.
- The coldest September reading, 6°C (43°F) on September 27, 1987, has not been matched in 39 years.
At least 1 mm of rain falls on 29% of September days, and the month averages 139 mm in total.
Warmest: 2015 (28.0°C)Latest: 2025 (26.2°C)10-year averageLong-run average (25.9°C)
Look Up a Day in September
See the weather in Seoul on any September date, year by year.
Source: NOAA GHCN-Daily, Seoul City (1973–2025); Incheon (1971–2026). Averages cover 1971–2026. How we compute this