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Iruma Weather by Month
Average temperatures, rainfall and humidity for Iruma, Japan, month by month, built from OpenWeather's historical records. Use it to see what a typical Iruma month looks like before you travel — then check the live Iruma forecast for the days ahead.
Warmest month
August
32°C average high
Coolest month
January
0°C average low
Wettest month
June
186 mm of rain
Driest month
January
25 mm of rain
Average temperature and rainfall in Iruma by month
Averages of the daily highs and lows recorded in each month, with total rainfall, mean humidity and mean wind speed.
| Month | Avg high | Avg low | Record low / high | Rainfall | Humidity | Wind |
|---|---|---|---|---|---|---|
| January | 10°C | 0°C | -13°C / 17°C | 25 mm | 55% | 11 km/h |
| February | 11°C | 2°C | -10°C / 25°C | 37 mm | 56% | 12 km/h |
| March | 15°C | 6°C | -6°C / 28°C | 81 mm | 62% | 12 km/h |
| April | 19°C | 11°C | -3°C / 29°C | 103 mm | 64% | 12 km/h |
| May | 24°C | 15°C | 3°C / 33°C | 114 mm | 67% | 12 km/h |
| June | 26°C | 19°C | 10°C / 37°C | 186 mm | 76% | 10 km/h |
| July | 31°C | 24°C | 17°C / 38°C | 110 mm | 77% | 11 km/h |
| August | 32°C | 25°C | 16°C / 41°C | 138 mm | 75% | 11 km/h |
| September | 28°C | 20°C | 8°C / 37°C | 145 mm | 78% | 10 km/h |
| October | 22°C | 14°C | 1°C / 33°C | 148 mm | 75% | 9 km/h |
| November | 17°C | 9°C | -4°C / 26°C | 54 mm | 69% | 9 km/h |
| December | 12°C | 3°C | -10°C / 23°C | 30 mm | 60% | 10 km/h |
Best time to visit Iruma
The most comfortable time to visit Iruma is generally April to May and October, balancing mild daytime temperatures against the driest stretch of the year. The city has strongly marked seasons and rain concentrates around June, totalling about 1171 mm a year.
Travellers who prefer heat should aim for August, when highs average 32°C. June is the month to avoid if rain would spoil your plans — it averages 186 mm, roughly 7× the rainfall of January.
Source: OpenWeather historical and statistical weather data. Values are long-term averages, not a forecast — see the Iruma forecast for what is happening now.