Climate Insights for Karatsu

The climate in Karatsu is temperate. The average annual temperature is 17°C and approximately 1894mm of precipitation falls per year. Karatsu receives a notable amount of rainfall throughout the year, including during its driest month. Karatsu 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 5°C. Light snow can occur between January and February.

Temperatures in Karatsu vary considerably across the year, with a 26°C difference between the coldest and warmest months. The warmest month is August, when average highs reach 31°C and the mean temperature sits around 28°C. February 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 5°C between highs and lows. The sharpest temperature change occurs between October and November, with a 5°C shift in average temperatures.

Karatsu is a fairly wet location, receiving approximately 1894mm of precipitation annually, which averages out to around 158mm per month. The wettest month is July, averaging 350mm of rainfall. June and September also tend to see above-average precipitation. The driest month is November, with just 67mm. That's 283mm less than July, 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. Light snowfall can occur between January and February, totalling around 7cm annually. January is the snowiest month with approximately 4cm.

Karatsu is relatively calm, with an average annual wind speed of 3km/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 4km/h, though still comfortable for most outdoor activities. The calmest conditions occur in May, with average winds dropping to 3km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 1km/h between the calmest and windiest months.

It is currently summer in Karatsu, which began on June 21, 2026. Karatsu 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 31°C, while the coldest stretch bottoms out in February near 5°C. Autumn is next, beginning on September 23, 2026 — 92 days from now.

The table below shows monthly climate averages for Karatsu 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.