Seoul weather in September
In September, Seoul has an average high of 25 °C76 °F and an average low of 17 °C62 °F, with about 138 mm5.4 in of precipitation. It is the 4th warmest month of the year and ranks 3rd for precipitation.
How September compares with other months
Compared with August, September is 4.5 °C8.2 °F cooler on average and drier by 123 mm4.8 in. Compared with October, September is 6.4 °C11.6 °F warmer on average and wetter by 84 mm3.3 in. Daylight lasts about 12.4 hours around the middle of the month. Average relative humidity is 79% and the average cloud amount 57%.
Is September a good time to visit Seoul?
September is not among the most comfortable months by our comfort score: it is fairly wet (138 mm5.4 in). The most comfortable months in Seoul are May and October.
What to wear in September
For Seoul in September, pack light summer clothes such as T-shirts, shorts or light dresses and an umbrella or light rain jacket.
September in nearby places
| Place | High °C°F | Low °C°F | Precip. mmin |
|---|---|---|---|
| Seoul | 2576 | 1762 | 1385.4 |
| Hanam | 2577 | 1559 | 1415.6 |
| Paju | 2576 | 1559 | 1305.1 |
| Yangju | 2476 | 1559 | 1305.1 |
| Suwon | 2476 | 1662 | 1385.4 |
| Hwaseong-si | 2476 | 1763 | 1345.3 |
| Osan | 2476 | 1763 | 1345.3 |
| Kaesŏng | 2476 | 1560 | 1184.6 |
| Chuncheon | 2475 | 1559 | 1395.5 |
Nearby places that are more than 1 °C1.8 °F cooler: Yangju and Chuncheon.
Other months in Seoul
- January1 °C33 °F / −7 °C20 °F
- February3 °C38 °F / −5 °C23 °F
- March9 °C48 °F / −1 °C30 °F
- April15 °C60 °F / 5 °C40 °F
- May21 °C70 °F / 11 °C52 °F
- June26 °C78 °F / 17 °C62 °F
- July28 °C82 °F / 21 °C70 °F
- August28 °C83 °F / 22 °C71 °F
- September25 °C76 °F / 17 °C62 °F
- October19 °C65 °F / 10 °C49 °F
- November11 °C51 °F / 3 °C37 °F
- December3 °C37 °F / −4 °C24 °F
Frequently asked questions
How warm is Seoul in September?
In September the average high in Seoul is 25 °C (76 °F) and the average low is 17 °C (62 °F).
Does it rain a lot in Seoul in September?
On average about 138 mm (5.4 in) of precipitation falls in September; it ranks 3rd of the 12 months.
Is September the warmest month in Seoul?
No. The warmest month in Seoul is August, with an average high of 28 °C (83 °F). The coldest month is January, with an average low of -7 °C (20 °F).
How long is the day in Seoul in September?
In the middle of September the day in Seoul lasts about 12.4 hours from sunrise to sunset. The value is calculated from the position of the city and the sun.
How humid is Seoul in September?
The average relative humidity in September is about 79%. This is a long-term average for the whole day.
How cloudy is Seoul in September?
On average about 57% of the sky is covered by cloud in September. This is the mean cloud amount from satellite data, not the number of sunny days.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.