Jeju weather by month
Jeju runs from about 7°C in January to 29°C in August, with November the wettest month at 357 mm.
warmest month
August
29°C
coolest month
January
7°C
wettest month
November
357 mm
worst air month
March
24 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 7°C | 160 mm | 164 h | 13 |
| February | 9°C | 245 mm | 111 h | 15 |
| March | 10°C | 243 mm | 216 h | 24 |
| April | 16°C | 160 mm | 223 h | 20 |
| May | 19°C | 143 mm | 299 h | 16 |
| June | 23°C | 338 mm | 201 h | 13 |
| July | 28°C | 228 mm | 247 h | 11 |
| August | 29°C | 101 mm | 377 h | 16 |
| September | 27°C | 195 mm | 281 h | 9 |
| October | 20°C | 213 mm | 199 h | 8 |
| November | 15°C | 357 mm | 207 h | 14 |
| December | 8°C | 57 mm | 178 h | 10 |
About 2,703 hours of sun a year. Roughly 235 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 2026-05-24. Full method, licences and the list of sources we rejected are on the methodology page.