Average annual temperature is 12.0 °C
Absolute maximum temperature: 29.9 °C
Absolute minimum temperature: -9.9 °C
Number of sunny days: 136 days
Number of rainy days: 225 days
Number of snow days: 4 days
Look at detailed online map of Iwanami
* Weather data for Iwanami 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) | 10.6 | 10.8 | 19.5 | 18.5 | 24.5 | 24.6 | 29.9 | 28.4 | 27.9 | 24.3 | 20.6 | 14.7 |
| Average daytime temperature (°C) | 5.2 | 6.4 | 11.4 | 14.1 | 17.3 | 21.3 | 25.5 | 26.6 | 24.5 | 17.6 | 13.4 | 8.7 |
| Average temperature (°C) | 0.8 | 2.3 | 7.4 | 10.4 | 13.5 | 17.8 | 21.6 | 22.5 | 20.8 | 13.3 | 9.2 | 3.9 |
| Average night temperature (°C) | -3.0 | -1.3 | 3.9 | 7.1 | 10.2 | 15.1 | 18.7 | 19.8 | 18.0 | 9.5 | 5.8 | 0.0 |
| Absolute minimum temperature (°C) | -9.9 | -6.2 | -3.3 | 0.2 | 4.6 | 11.9 | 15.5 | 17.7 | 13.0 | 6.0 | -1.6 | -8.5 |
| 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) | 6.9 | 6.6 | 7.7 | 8.3 | 8.2 | 6.8 | 9.4 | 10.5 | 9.2 | 8.7 | 7.4 | 7.3 |
| Precipitation (mm) | 41 | 111 | 217 | 268 | 317 | 647 | 164 | 221 | 202 | 160 | 121 | 100 |
| Sunny days | 15 | 12 | 11 | 10 | 11 | 7 | 10 | 4 | 7 | 14 | 15 | 20 |
| Rainy days | 14 | 14 | 20 | 20 | 20 | 23 | 21 | 27 | 23 | 17 | 15 | 11 |
| Snow days | 2 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
The best time to visit Iwanami during the most sunny months:
The largest precipitation sum in Iwanami is at