Climate Insights for Ōshima

The climate in Ōshima is temperate. The average annual temperature is 17°C and approximately 1748mm of precipitation falls per year. Ōshima receives a notable amount of rainfall throughout the year, including during its driest month. Ōshima 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.

Temperatures in Ōshima vary considerably across the year, with a 24°C difference between the coldest and warmest months. The warmest month is August, when average highs reach 29°C and the mean temperature sits around 28°C. January is the coolest month, with minimum temperatures around 5°C and an average of 7°C. Daily temperature variation is modest, with an average difference of 4°C between highs and lows. The sharpest temperature change occurs between November and December, with a 6°C shift in average temperatures.

Ōshima is a fairly wet location, receiving approximately 1748mm of precipitation annually, which averages out to around 146mm per month. The wettest month is July, averaging 261mm of rainfall. June and September also tend to see above-average precipitation. The driest month is January, with just 67mm. That's 194mm less than July, the wettest month. Precipitation varies noticeably between seasons, with the second half (July to December) of the year generally seeing more rainfall.

Ōshima is mildly breezy, with an average annual wind speed of 19km/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 June, with average winds dropping to 15km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 7km/h gap 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 22km/h in winter, 18km/h in spring, 15km/h in summer, 19km/h in autumn.

It is currently spring in Ōshima, which began on March 20, 2026. Ōshima 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 29°C, while the coldest stretch bottoms out in January near 5°C. Summer is next, beginning on June 21, 2026 — 88 days from now.

The table below shows monthly climate averages for Ōshima 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.