Climate Insights for Iiyama

The climate in Iiyama is temperate. The average annual temperature is 11°C and approximately 1968mm of precipitation falls per year. Iiyama receives a notable amount of rainfall throughout the year, including during its driest month. Iiyama 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 -5°C. Iiyama experiences heavy snowfall, typically from January through December.

Temperatures in Iiyama vary considerably across the year, with a 33°C difference between the coldest and warmest months. The warmest month is August, when average highs reach 28°C and the mean temperature sits around 24°C. The coldest month is January, when overnight lows fall to -5°C and the daily average is -2°C. Daily temperature variation is modest, with an average difference of 8°C between highs and lows. The sharpest temperature change occurs between September and October, with a 7°C shift in average temperatures.

Iiyama is a fairly wet location, receiving approximately 1968mm of precipitation annually, which averages out to around 164mm per month. The wettest month is July, averaging 279mm of rainfall. September and August also tend to see above-average precipitation. The driest month is February, with just 120mm. That's 159mm less than July, the wettest month. Rainfall is relatively evenly distributed throughout the year, so there is no pronounced dry or wet season to plan around. Iiyama receives heavy snowfall, accumulating around 281cm annually from January through December. The snowiest month is January, with approximately 92cm. Winter travel should account for significant snow cover.

Iiyama is relatively calm, with an average annual wind speed of 9km/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 11km/h, though still comfortable for most outdoor activities. The calmest conditions occur in July, with average winds dropping to 7km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 4km/h gap between the calmest and windiest months.

It is currently spring in Iiyama, which began on March 20, 2026. Iiyama 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 28°C, while the coldest stretch bottoms out in January near -5°C. Summer is next, beginning on June 21, 2026 — 89 days from now.

The table below shows monthly climate averages for Iiyama 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.