Average annual temperature is 15.8 °C
Absolute maximum temperature: 34.5 °C
Absolute minimum temperature: -5.0 °C
Number of sunny days: 133 days
Number of rainy days: 228 days
Number of snow days: 4 days
Look at detailed online map of Seiyo
* Weather data for Seiyo Japan is based on climate observations for 2026 year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Absolute maximum temperature (°C) | 19.7 | 17.2 | 23.8 | 25.8 | 29.6 | 31.8 | 34.5 | 34.4 | 33.5 | 27.7 | 25.4 | 22.3 |
| Average daytime temperature (°C) | 9.3 | 11.4 | 17.3 | 19.7 | 23.5 | 26.0 | 30.8 | 30.6 | 30.1 | 22.7 | 17.7 | 11.9 |
| Average temperature (°C) | 4.8 | 5.9 | 11.1 | 14.2 | 18.2 | 21.6 | 26.2 | 26.4 | 24.9 | 16.5 | 12.3 | 7.1 |
| Average night temperature (°C) | 1.3 | 1.1 | 6.0 | 9.2 | 13.6 | 17.8 | 22.4 | 23.4 | 21.1 | 11.7 | 8.3 | 3.1 |
| Absolute minimum temperature (°C) | -5.0 | -4.0 | -2.7 | 3.2 | 6.7 | 12.4 | 18.2 | 21.1 | 15.9 | 5.2 | 1.7 | -2.7 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight maximum duration (h) | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 14.0 | 14.0 | 13.0 | 12.0 | 11.0 | 10.0 | 10.0 |
| Daylight mean duration (h) | 10.2 | 11.0 | 12.0 | 13.0 | 13.9 | 14.3 | 14.1 | 13.4 | 12.4 | 11.4 | 10.5 | 10.0 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 13.0 | 12.0 | 11.0 | 10.0 | 10.0 | 9.0 |
| Sunshine mean duration (h) | 6.7 | 7.2 | 8.6 | 8.1 | 8.9 | 6.1 | 10.1 | 9.7 | 9.7 | 8.8 | 7.8 | 6.8 |
| Precipitation (mm) | 76 | 62 | 104 | 214 | 222 | 345 | 122 | 192 | 67 | 22 | 71 | 97 |
| Sunny days | 13 | 14 | 18 | 15 | 15 | 10 | 4 | 0 | 4 | 20 | 12 | 8 |
| Rainy days | 17 | 14 | 13 | 15 | 16 | 20 | 27 | 31 | 26 | 11 | 18 | 20 |
| Snow days | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 |
The largest precipitation sum in Seiyo is at