WEATHER · CLIMATE NORMALS · 1991–2020
Osaka Climate — Averages by Month
What the weather in Osaka, JPaverages 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 | 5.4 °C · coldest | 62.3 mm |
| February | 5.9 °C | 70.8 mm |
| March | 9.2 °C | 112.2 mm |
| April | 14.7 °C | 122.6 mm |
| May | 19.6 °C | 141.7 mm |
| June | 23.4 °C | 198.2 mm · wettest |
| July | 27.3 °C | 186.1 mm |
| August | 28.7 °C · warmest | 117.9 mm |
| September | 24.7 °C | 170.7 mm |
| October | 18.8 °C | 152.3 mm |
| November | 13.0 °C | 81.2 mm |
| December | 7.7 °C | 65.2 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 Osaka — centred at 34.75°N, 135.50°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.