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Iwatsuki Weather by Month
Average temperatures, rainfall and humidity for Iwatsuki, Japan, month by month, built from OpenWeather’s historical records. Use it to see what a typical Iwatsuki month looks like before you travel — then check the live Iwatsuki forecast for the days ahead.
Warmest month
August
32°C average high
Coolest month
January
1°C average low
Wettest month
June
174 mm of rain
Driest month
January
31 mm of rain
Average temperature and rainfall in Iwatsuki 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 | 1°C | -13°C / 18°C | 31 mm | 53% | 12 km/h |
| February | 11°C | 2°C | -7°C / 23°C | 45 mm | 56% | 12 km/h |
| March | 15°C | 6°C | -3°C / 27°C | 86 mm | 61% | 12 km/h |
| April | 20°C | 11°C | 1°C / 29°C | 105 mm | 63% | 12 km/h |
| May | 24°C | 16°C | 7°C / 34°C | 118 mm | 66% | 12 km/h |
| June | 27°C | 20°C | 13°C / 38°C | 174 mm | 71% | 10 km/h |
| July | 31°C | 24°C | 18°C / 39°C | 110 mm | 75% | 11 km/h |
| August | 32°C | 25°C | 17°C / 40°C | 136 mm | 72% | 12 km/h |
| September | 28°C | 21°C | 11°C / 37°C | 141 mm | 76% | 11 km/h |
| October | 22°C | 15°C | 5°C / 32°C | 148 mm | 73% | 11 km/h |
| November | 17°C | 9°C | -1°C / 27°C | 65 mm | 64% | 10 km/h |
| December | 12°C | 4°C | -6°C / 23°C | 36 mm | 57% | 11 km/h |
Best time to visit Iwatsuki
The most comfortable time to visit Iwatsuki 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 1,195 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 174 mm, roughly 6× the rainfall of the driest month (January).
Source: OpenWeather historical and statistical weather data. Values are long-term averages, not a forecast — see the Iwatsuki forecast for what is happening now.