Climate Insights for Iwamizawa

The climate in Iwamizawa is cool. The average annual temperature is 7°C and approximately 1262mm of precipitation falls per year. Iwamizawa receives a notable amount of rainfall throughout the year, including during its driest month. Iwamizawa is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: August, July, September. The coldest months are January, February, December, when temperatures can drop to -10°C. Iwamizawa experiences heavy snowfall, typically from January through December.

Temperatures in Iwamizawa vary considerably across the year, with a 34°C difference between the coldest and warmest months. August is the warmest month, though highs remain moderate at 24°C with a mean of 20°C. The coldest month is January, when overnight lows fall to -10°C and the daily average is -7°C. Daily temperature variation is modest, with an average difference of 7°C between highs and lows. The sharpest temperature change occurs between October and November, with a 8°C shift in average temperatures.

Iwamizawa is a fairly wet location, receiving approximately 1262mm of precipitation annually, which averages out to around 105mm per month. The wettest month is August, averaging 208mm of rainfall. November and July also tend to see above-average precipitation. The driest month is January, with just 67mm. That's 141mm less than August, the wettest month. Precipitation varies noticeably between seasons, with the second half (July to December) of the year generally seeing more rainfall. Iwamizawa receives heavy snowfall, accumulating around 324cm annually from January through December. The snowiest month is December, with approximately 76cm. Winter travel should account for significant snow cover.

Iwamizawa is relatively calm, with an average annual wind speed of 3km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is April, averaging 3km/h, though still comfortable for most outdoor activities. The calmest conditions occur in August, with average winds dropping to 3km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 0km/h between the calmest and windiest months.

It is currently spring in Iwamizawa, which began on March 20, 2026. Iwamizawa is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in August at around 24°C, while the coldest stretch bottoms out in January near -10°C. Summer is next, beginning on June 21, 2026 — 3 days from now.

The table below shows monthly climate averages for Iwamizawa based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.