Hiroshima weather by month
Hiroshima runs from about 5°C in January to 28°C in August, with June the wettest month at 287 mm.
warmest month
August
28°C
coolest month
January
5°C
wettest month
June
287 mm
worst air month
March
17 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 5°C | 48 mm | 223 h | 13 |
| February | 7°C | 143 mm | 190 h | 16 |
| March | 8°C | 162 mm | 240 h | 17 |
| April | 15°C | 142 mm | 210 h | 16 |
| May | 17°C | 187 mm | 300 h | 11 |
| June | 21°C | 287 mm | 252 h | 12 |
| July | 27°C | 249 mm | 300 h | 12 |
| August | 28°C | 183 mm | 342 h | 14 |
| September | 26°C | 63 mm | 322 h | 9 |
| October | 19°C | 146 mm | 214 h | 8 |
| November | 13°C | 235 mm | 240 h | 14 |
| December | 6°C | 6 mm | 259 h | 13 |
About 3,092 hours of sun a year. Roughly 186 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 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.