Average annual temperature is 16.6 °C
Absolute maximum temperature: 40.6 °C
Absolute minimum temperature: -4.8 °C
Number of sunny days: 175 days
Number of rainy days: 187 days
Number of snow days: 3 days
Look at detailed online map of Koizumi
* Weather data for Koizumi 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) | 13.6 | 17.9 | 23.6 | 28.7 | 32.1 | 32.2 | 40.6 | 38.8 | 34.9 | 26.7 | 27.5 | 19.4 |
| Average daytime temperature (°C) | 9.2 | 11.3 | 17.8 | 21.7 | 23.8 | 27.0 | 34.1 | 33.9 | 30.5 | 22.8 | 17.8 | 12.7 |
| Average temperature (°C) | 4.0 | 5.8 | 12.1 | 15.4 | 18.2 | 22.6 | 28.4 | 28.7 | 26.0 | 17.6 | 12.2 | 7.1 |
| Average night temperature (°C) | -0.2 | 1.1 | 6.9 | 10.1 | 13.5 | 18.9 | 24.0 | 25.0 | 22.8 | 13.1 | 7.8 | 2.8 |
| Absolute minimum temperature (°C) | -4.8 | -3.0 | 0.7 | 3.9 | 7.2 | 11.3 | 21.1 | 23.1 | 15.7 | 8.2 | 1.9 | -3.2 |
| 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 | 9.0 |
| Daylight mean duration (h) | 10.0 | 10.9 | 12.0 | 13.1 | 14.1 | 14.6 | 14.3 | 13.5 | 12.4 | 11.3 | 10.3 | 9.8 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 14.0 | 12.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 7.4 | 8.0 | 8.0 | 8.8 | 9.0 | 7.7 | 9.8 | 10.6 | 8.6 | 8.4 | 7.5 | 7.8 |
| Precipitation (mm) | 14 | 35 | 101 | 55 | 181 | 305 | 75 | 129 | 167 | 86 | 62 | 18 |
| Sunny days | 21 | 19 | 19 | 15 | 14 | 6 | 9 | 6 | 6 | 16 | 21 | 23 |
| Rainy days | 8 | 8 | 12 | 15 | 17 | 24 | 22 | 25 | 24 | 15 | 9 | 8 |
| Snow days | 2 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
The largest precipitation sum in Koizumi is at