Climate Insights for Koshima

The climate in Koshima is warm and mild. The average annual temperature is 21°C and approximately 2645mm of precipitation falls per year. Koshima receives a notable amount of rainfall throughout the year, including during its driest month. Koshima 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 February, January, December, when temperatures can drop to 13°C.

Koshima sees moderate temperature variation throughout the year, ranging from 13°C to 28°C. The warmest month is August, when average highs reach 28°C and the mean temperature sits around 28°C. February is the coolest month, with minimum temperatures around 13°C and an average of 14°C. Daily temperature variation is modest, with an average difference of 2°C between highs and lows. The sharpest temperature change occurs between November and December, with a 5°C shift in average temperatures.

Koshima is a very wet location, receiving approximately 2645mm of precipitation annually, which averages out to around 220mm per month. The wettest month is June, averaging 501mm of rainfall. May and July also tend to see above-average precipitation. The driest month is January, with just 134mm. That's 368mm less than June, the wettest month. Precipitation varies noticeably between seasons, with the first half (January to June) of the year generally seeing more rainfall.

Koshima is very windy, with an average annual wind speed of 36km/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 41km/h, which can feel quite blustery and may affect outdoor activities. The calmest conditions occur in August, with average winds dropping to 31km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 10km/h between the calmest and windiest months. Wind tends to be stronger during winter months, driven by seasonal pressure systems. The seasonal averages break down to 40km/h in winter, 36km/h in spring, 32km/h in summer, 35km/h in autumn.

It is currently spring in Koshima, which began on March 20, 2026. Koshima 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 February near 13°C. Summer is next, beginning on June 21, 2026 — 88 days from now.

The table below shows monthly climate averages for Koshima 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. 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.