Seoul weather by month
Seoul runs from about -2°C in January to 27°C in August, with July the wettest month at 522 mm.
warmest month
August
27°C
coolest month
January
-2°C
wettest month
July
522 mm
worst air month
March
47 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -2°C | 17 mm | 223 h | 26 |
| February | 2°C | 64 mm | 157 h | 33 |
| March | 5°C | 51 mm | 270 h | 47 |
| April | 14°C | 40 mm | 255 h | 30 |
| May | 17°C | 127 mm | 298 h | 29 |
| June | 23°C | 110 mm | 331 h | 24 |
| July | 25°C | 522 mm | 219 h | 22 |
| August | 27°C | 182 mm | 343 h | 26 |
| September | 24°C | 210 mm | 263 h | 24 |
| October | 15°C | 75 mm | 224 h | 21 |
| November | 8°C | 42 mm | 225 h | 35 |
| December | -1°C | 3 mm | 246 h | 30 |
About 3,054 hours of sun a year. Roughly 122 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-22. Full method, licences and the list of sources we rejected are on the methodology page.