Climate Overview
The climate in Iwanuma is temperate. The average annual temperature is 13°C and approximately 1383mm of precipitation falls per year. Iwanuma receives a notable amount of rainfall throughout the year, including during its driest month. Iwanuma 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 -1°C. Snowfall occurs from January to December, with around 58cm accumulating over the season.
Temperature
Temperatures in Iwanuma vary considerably across the year, with a 29°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 25°C. The coldest month is January, when overnight lows fall to -1°C and the daily average is 2°C. Daily temperature variation is modest, with an average difference of 6°C between highs and lows. The sharpest temperature change occurs between September and October, with a 6°C shift in average temperatures.
Precipitation
Iwanuma is a fairly wet location, receiving approximately 1383mm of precipitation annually, which averages out to around 115mm per month. The wettest month is August, averaging 209mm of rainfall. September and July also tend to see above-average precipitation. The driest month is February, with just 45mm. That's 164mm 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. Snowfall is a regular feature from January to December, with around 58cm accumulating over the season. January typically sees the most snow at around 20cm.
Wind
Iwanuma is mildly breezy, with an average annual wind speed of 17km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is January, averaging 22km/h, noticeable enough to affect lighter outdoor activities. The calmest conditions occur in July, with average winds dropping to 11km/h, making it an ideal period for wind-sensitive activities. Wind speeds vary significantly across the year, with a 11km/h difference between the calmest and windiest months. This level of variation is worth factoring into travel plans. Wind tends to be stronger during winter months, driven by seasonal pressure systems. The seasonal averages break down to 21km/h in winter, 18km/h in spring, 12km/h in summer, 16km/h in autumn.
Seasons
89 days until Summer
It is currently spring in Iwanuma, which began on March 20, 2026. Iwanuma 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 -1°C. Summer is next, beginning on June 21, 2026 — 89 days from now.
Spring
Temperatures range from 3 to 20°C. Rainfall is heavy, totalling around 306mm across the season with a monthly average of 102mm. Winds are moderate at around 18km/h. An umbrella or waterproof jacket is advisable as spring showers are frequent.
Summer
Temperatures range from 17 to 28°C. Rainfall is heavy, totalling around 525mm across the season with a monthly average of 175mm. Winds are generally light, averaging 12km/h. Light, breathable clothing is ideal — perfect conditions for outdoor activities.
Autumn
Temperatures range from 6 to 24°C. Rainfall is heavy, totalling around 397mm across the season with a monthly average of 132mm. Winds are moderate at around 16km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.
Winter
Temperatures range from -1 to 7°C. Precipitation is moderate at around 154mm for the season, averaging 51mm per month. Expect around 42cm of snow accumulation during this period. Winds are moderate at around 21km/h. Warm winter clothing and waterproof boots are a must, and travel may be affected by snow.
Monthly Climate Data
The table below shows monthly climate averages for Iwanuma 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.
