WEATHER · CLIMATE NORMALS · 1991–2020
Seoul Climate — Averages by Month
What the weather in Seoul, KRaverages across a standard 30-year period. Each month's figure is the 1991–2020 mean temperature and total rainfall from the ERA5 reanalysis — the long-run normal a place settles around, not a forecast for any particular day.
Month-by-month normals
| Month | Avg temperature | Avg rainfall |
|---|---|---|
| January | -2.7 °C · coldest | 21.3 mm |
| February | -0.1 °C | 27.9 mm |
| March | 5.3 °C | 39.6 mm |
| April | 11.9 °C | 72.1 mm |
| May | 17.5 °C | 97.8 mm |
| June | 22.1 °C | 137.5 mm |
| July | 25.0 °C | 316.3 mm · wettest |
| August | 25.5 °C · warmest | 259.6 mm |
| September | 20.8 °C | 126.1 mm |
| October | 13.9 °C | 55.2 mm |
| November | 6.5 °C | 48.8 mm |
| December | -0.7 °C | 25.4 mm |
How to read these numbers
These are reanalysis normals, not readings from a single weather station. They come from the ERA5 0.25° (~25 km) global reanalysis grid, sampled at the grid cell nearest Seoul — centred at 37.50°N, 127.00°E. A reanalysis blends observations with a physics model onto an even grid, so a coastal or mountain city's cell can read a little cooler, warmer, wetter or drier than the city centre itself. The month-to-month shape — when it's hot, when it rains — is what these normals capture best.
“Normal” means the 1991–2020 average, the current World Meteorological Organization standard period. A normal is what a place tends toward over decades — any single day, month or year can and will depart from it.