Okayama weather by month
Okayama runs from about 5°C in January to 29°C in August, with June the wettest month at 306 mm.
warmest month
August
29°C
coolest month
January
5°C
wettest month
June
306 mm
worst air month
March
17 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 5°C | 29 mm | 217 h | 11 |
| February | 7°C | 115 mm | 194 h | 15 |
| March | 8°C | 130 mm | 249 h | 17 |
| April | 16°C | 185 mm | 227 h | 15 |
| May | 18°C | 183 mm | 296 h | 10 |
| June | 22°C | 306 mm | 262 h | 13 |
| July | 28°C | 249 mm | 305 h | 11 |
| August | 29°C | 184 mm | 342 h | 15 |
| September | 27°C | 51 mm | 308 h | 10 |
| October | 20°C | 149 mm | 219 h | 8 |
| November | 13°C | 109 mm | 230 h | 13 |
| December | 6°C | 1 mm | 257 h | 11 |
About 3,106 hours of sun a year. Roughly 169 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.