September is close to Korea's year-round average, with average highs near 31°C and lows around 19.9°C (mean 25.5°C). It is a relatively wet time of year, averaging 209 mm of rainfall and 87% relative humidity across the period.
September is close to Korea's year-round average. Across 45 years of records, the warmest September in Korea was 2004 — when the month averaged 26.7°C — while the coldest was 1982 at 23.4°C. Typical September days reach 31°C with nights near 19.9°C. The long-term trend is warming, about 0.2°C per decade.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 25.4°C | 25.2°C | 25.6°C | 25.2°C | 26.2°C | +0.8°C |
| Avg High | 31.1°C | 30.5°C | 31.3°C | 31.0°C | 30.9°C | -0.2°C |
| Avg Low | 19.6°C | 19.8°C | 19.8°C | 19.4°C | 21.5°C | +1.9°C |
| Avg Rain | 173 mm | 222 mm | 198 mm | 234 mm | 219 mm | +46 mm |
September temperatures in Korea have risen by about 1.3°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 15.5°C (1982) to a record high of 32.8°C (2004).
Rainfall in September is a relatively wet time of year, averaging 209 mm, with a wettest year of 460 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0°C per decade while lows rose 0.3°C per decade, narrowing the gap between day and night.
A good time to visit Korea
September is a good time to visit Korea, with days averaging 31°C and nights around 19.9°C (mean 25.5°C, close to Korea's yearly average) and higher rainfall. February and October are marginally more temperate, but September still suits most travellers.
| Year | High | Low | Avg | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|
| 2025 | 30.7°C | 21.6°C | 26.2°C | 204 mm | 88% | 1.5 m/s | 4.1 |
| 2024 | 30.8°C | 22.0°C | 26.4°C | 176 mm | 90% | 2.2 m/s | 4 |
| 2023 | 31.0°C | 22.0°C | 26.5°C | 319 mm | 89% | 1.8 m/s | 4.3 |
| 2022 | 30.4°C | 20.8°C | 25.6°C | 238 mm | 89% | 1.9 m/s | 3.9 |
| 2021 | 31.1°C | 21.9°C | 26.5°C | 254 mm | 89% | 2.1 m/s | 4.4 |
| 2020 | 31.4°C | 20.6°C | 26.0°C | 125 mm | 87% | 1.4 m/s | 4.4 |
| 2019 | 31.1°C | 20.9°C | 26.0°C | 365 mm | 90% | 2.2 m/s | 4 |
| 2018 | 30.6°C | 19.6°C | 25.1°C | 124 mm | 86% | 2 m/s | 4.5 |
| 2017 | 31.1°C | 19.7°C | 25.4°C | 165 mm | 85% | 1.3 m/s | 4.6 |
| 2016 | 30.4°C | 21.5°C | 26.0°C | 233 mm | 89% | 1.6 m/s | 4 |
| 2015 | 31.4°C | 18.0°C | 24.7°C | 223 mm | 83% | 1.6 m/s | 5.3 |
| 2014 | 30.7°C | 18.5°C | 24.6°C | 207 mm | 86% | 1.7 m/s | 4.6 |
| 2013 | 30.9°C | 20.3°C | 25.6°C | 178 mm | 86% | 1.5 m/s | 5 |
| 2012 | 31.2°C | 18.5°C | 24.9°C | 174 mm | 87% | 1.6 m/s | 4.4 |
| 2011 | 30.6°C | 20.0°C | 25.3°C | 391 mm | 90% | 2 m/s | 4.1 |
| 2010 | 31.5°C | 17.1°C | 24.3°C | 286 mm | 85% | 1.6 m/s | 4.8 |
| 2009 | 31.5°C | 19.9°C | 25.7°C | 76 mm | 84% | 2.1 m/s | 5 |
| 2008 | 31.0°C | 18.9°C | 24.9°C | 206 mm | 87% | 1.9 m/s | 5.3 |
| 2007 | 30.9°C | 21.4°C | 26.2°C | 332 mm | 89% | 1.8 m/s | 4.3 |
| 2006 | 30.5°C | 17.8°C | 24.2°C | 143 mm | 85% | 1.9 m/s | 5 |
| 2005 | 31.9°C | 19.4°C | 25.7°C | 238 mm | 88% | 2.1 m/s | 4.4 |
| 2004 🔥 | 32.8°C | 20.6°C | 26.7°C | 134 mm | 84% | 1.6 m/s | 5 |
| 2003 | 30.5°C | 21.7°C | 26.1°C | 419 mm | 91% | 2.1 m/s | 3.7 |
| 2002 | 30.3°C | 18.5°C | 24.4°C | 202 mm | 87% | 2.1 m/s | 5 |
| 2001 | 31.1°C | 19.9°C | 25.5°C | 68 mm | 84% | 1.7 m/s | 5.2 |
| 2000 | 32.7°C | 20.0°C | 26.4°C | 156 mm | 81% | 2.2 m/s | 4.2 |
| 1999 | 30.1°C | 21.6°C | 25.9°C | 252 mm | 89% | 1.5 m/s | 4.5 |
| 1998 | 30.8°C | 22.2°C | 26.5°C | 325 mm | 88% | 1.6 m/s | 4.8 |
| 1997 | 30.3°C | 18.7°C | 24.5°C | 157 mm | 87% | 1.7 m/s | 4.7 |
| 1996 | 30.8°C | 19.5°C | 25.2°C | 79 mm | 86% | 1.4 m/s | 5 |
| 1995 | 30.9°C | 19.4°C | 25.1°C | 138 mm | 87% | 2 m/s | 4.8 |
| 1994 | 30.4°C | 17.3°C | 23.9°C | 236 mm | 85% | 1.8 m/s | 4.9 |
| 1993 🌧️ | 30.0°C | 21.4°C | 25.7°C | 460 mm | 90% | 2.1 m/s | 3.6 |
| 1992 | 31.0°C | 18.3°C | 24.7°C | 219 mm | 85% | 1.8 m/s | 5 |
| 1991 | 30.3°C | 18.2°C | 24.3°C | 80 mm | 87% | 1.8 m/s | 4.9 |
| 1990 | 30.7°C | 21.6°C | 26.2°C | 273 mm | 89% | 1.8 m/s | 4.1 |
| 1989 | 31.0°C | 21.1°C | 26.1°C | 144 mm | 87% | 1.6 m/s | 4.6 |
| 1988 | 31.4°C | 21.6°C | 26.5°C | 123 mm | 86% | 1.5 m/s | 5.1 |
| 1987 | 31.9°C | 20.2°C | 26.0°C | 193 mm | 86% | 2.3 m/s | 3.9 |
| 1986 | 32.5°C | 18.6°C | 25.5°C | 119 mm | 82% | 1.9 m/s | 5.2 |
| 1985 | 30.6°C | 20.0°C | 25.3°C | 230 mm | 87% | 1.8 m/s | 5.1 |
| 1984 | 30.1°C | 17.4°C | 23.7°C | 105 mm | 86% | 1.9 m/s | 5.1 |
| 1983 | 30.7°C | 21.6°C | 26.2°C | 314 mm | 89% | 1.5 m/s | — |
| 1982 ❄️ | 31.4°C | 15.5°C | 23.4°C | 111 mm | 84% | 1.7 m/s | — |
| 1981 | 30.7°C | 20.6°C | 25.7°C | 220 mm | 87% | 1.8 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 31°C with lows near 19.9°C (mean 25.5°C), based on 45 years of NASA POWER data.
September averages 209 mm of rainfall in Korea, a relatively wet time of year. The wettest on record was 460 mm in 1993.
The hottest September reached 32.8°C in 2004. The coldest dipped to 15.5°C in 1982.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.3°C. Daytime highs moved from 30.7°C to 30.8°C and overnight lows from 19°C to 21.7°C over the same span.
September is close to Korea's year-round average and a relatively wet time of year, so plan for around 31°C daytime highs and 19.9°C at night.
Not quite — September is the 6th coolest month in Korea, averaging 25.5°C.
For September in Korea, pack light, breathable clothing and sun protection, with typical highs of 31°C and lows of 19.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 87% — quite humid.
Average wind speed in September is 1.8 m/s. The windiest September on record averaged 2.3 m/s (1987).
The wettest September on record was 1993 with 460 mm. On average, September sees 209 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Korea behaves each September, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for September specifically, along with year-by-year records and how the month has changed over the decades.
