Average annual temperature is 17.5 °C
Absolute maximum temperature: 33.9 °C
Absolute minimum temperature: -2.8 °C
Number of sunny days: 137 days
Number of rainy days: 227 days
Number of snow days: 1 day
Look at detailed online map of Isumi
* Weather data for Isumi 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) | 16.3 | 19.1 | 25.1 | 24.8 | 26.8 | 30.1 | 33.0 | 33.9 | 31.8 | 30.6 | 25.1 | 22.7 |
| Average daytime temperature (°C) | 10.2 | 11.6 | 16.1 | 19.1 | 21.0 | 25.1 | 29.9 | 30.9 | 28.8 | 22.7 | 19.2 | 14.3 |
| Average temperature (°C) | 6.5 | 8.2 | 13.1 | 16.0 | 18.3 | 22.1 | 26.5 | 27.6 | 26.1 | 19.0 | 15.7 | 10.5 |
| Average night temperature (°C) | 3.2 | 4.6 | 10.2 | 13.3 | 15.9 | 19.9 | 23.7 | 25.3 | 24.0 | 15.5 | 12.8 | 7.0 |
| Absolute minimum temperature (°C) | -2.8 | -0.3 | 2.8 | 6.9 | 11.4 | 16.6 | 20.7 | 23.0 | 20.9 | 12.1 | 6.4 | 0.9 |
| 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) | 10.1 | 10.9 | 12.0 | 13.1 | 14.0 | 14.5 | 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 | 13.0 | 12.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 6.5 | 7.1 | 7.5 | 8.9 | 8.5 | 7.3 | 10.9 | 11.7 | 9.1 | 8.9 | 7.2 | 7.4 |
| Precipitation (mm) | 60 | 99 | 170 | 179 | 137 | 255 | 33 | 110 | 181 | 166 | 82 | 46 |
| Sunny days | 13 | 13 | 7 | 12 | 12 | 5 | 18 | 4 | 4 | 14 | 15 | 20 |
| Rainy days | 17 | 15 | 24 | 18 | 19 | 25 | 13 | 27 | 26 | 17 | 15 | 11 |
| Snow days | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
The best time to visit Isumi during the most sunny months:
The largest precipitation sum in Isumi is at