Climate Insights for Unzen

The climate in Unzen is warm and mild. The average annual temperature is 18°C and approximately 2222mm of precipitation falls per year. Unzen receives a notable amount of rainfall throughout the year, including during its driest month. Unzen 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 Unzen vary considerably across the year, with a 28°C difference between the coldest and warmest months. The warmest month is August, when average highs reach 33°C and the mean temperature sits around 29°C. January is the coolest month, with minimum temperatures around 5°C and an average of 8°C. Daily temperature variation is modest, with an average difference of 7°C between highs and lows. The sharpest temperature change occurs between November and December, with a 6°C shift in average temperatures.

Unzen is a very wet location, receiving approximately 2222mm of precipitation annually, which averages out to around 185mm per month. The wettest month is June, averaging 412mm of rainfall. July and August also tend to see above-average precipitation. The driest month is January, with just 75mm. That's 336mm less than June, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic.

Unzen is mildly breezy, with an average annual wind speed of 14km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is February, averaging 16km/h, though still comfortable for most outdoor activities. The calmest conditions occur in May, with average winds dropping to 13km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 3km/h between the calmest and windiest months.

It is currently spring in Unzen, which began on March 20, 2026. Unzen 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 33°C, while the coldest stretch bottoms out in January near 5°C. Summer is next, beginning on June 21, 2026 — 87 days from now.

The table below shows monthly climate averages for Unzen 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.