Karatsu

Planning a trip or just a stroll through the city of Karatsu? Here you will find the latest information on weather conditions, as well as up-to-date forecasts and useful charts.

The city of Karatsu in Japan has a humid subtropical climate, characterized by clearly defined seasons. Overall, the weather here features mild winters and warm, humid summers. Temperature fluctuations throughout the year are significant, ranging from cool winter months to hot summer ones.

Winters in Karatsu (December to February) are quite mild, with average temperatures around 7-8°C and relatively low precipitation. Spring (March to May) brings gradual warming, with average temperatures rising from 11°C to nearly 19°C, and the number of rainy days increasing slightly. Summer (June to August) is the warmest and most humid period. Average temperatures reach 26-27.5°C, with August being particularly hot. Autumn (September to November) offers comfortable weather, with temperatures gradually decreasing from 24°C to 14°C and a reduction in rainfall.

The data shows that the summer months, especially July, stand out with the highest amount of precipitation (10 mm) and the maximum number of rainy days (18 days). This indicates a pronounced wet season during the summer period. The lowest amount of precipitation occurs in December (2 mm), while the fewest rainy days are in November (8 days).

The climate in Karatsu is characterized by noticeable seasonal temperature changes. Throughout the year, the thermometer fluctuates from cool winter values to hot summer ones. The coldest month is typically January, when the average temperature is around 7.0°C, with nighttime lows averaging 4.9°C and daytime highs around 9.0°C. In contrast, August is the hottest month, with an average temperature of 27.5°C, while daytime highs can reach nearly 30°C (averaging 29.8°C), and nights remain very warm, around 25.3°C.

The summer months in Karatsu, especially July and August, bring real heat. Average temperatures during this period stay confidently above 20°C. In June, the average temperature is 22.3°C (ranging from 20.0°C to 24.6°C); in July, it rises to 26.2°C (from 24.3°C to 28.2°C), reaching its peak in the aforementioned August. The difference between day and night temperatures in summer is not very large, indicating consistently warm and sometimes sweltering weather that can feel quite humid, given the high number of days with precipitation during the summer months.

Winter in Karatsu is relatively mild. From December to February, average temperatures range from 7.0°C to 8.4°C. Nighttime frosts are atypical, as minimum temperatures usually stay above 4.9°C (in January). During the day, the air warms up to 9-10°C. Transitional seasons—spring and autumn—offer comfortable weather. In April, the average temperature is a pleasant 15.0°C, and in October, it is a comfortable 19.3°C. Daily temperature fluctuations throughout the year are moderate, usually within 4-6°C between the average minimum and maximum, ensuring fairly predictable weather throughout the day.

The city of Karatsu experiences a distinct seasonality in the distribution of precipitation throughout the year. Although it rains year-round, the intensity and frequency vary significantly. The highest amount of rainfall occurs during the summer months, forming a clear rainy season.

The wettest month in Karatsu is July, when an average of 10 mm of precipitation falls, and the number of rainy days reaches 18. June (8 mm of precipitation, 14 rainy days) and August (8 mm of precipitation, 15 rainy days) are also characterized by significant rainfall and frequent rain. This summer period, which also includes May and September with increased precipitation and rainy days, can be considered the main wet season.

The driest month in terms of precipitation volume is December, with only 2 mm falling, although there are still about 9 rainy days in this month. November features the fewest rainy days—an average of 8, with 3 mm of precipitation. Overall, late autumn and winter (October, November, December, January, February) are characterized by lower precipitation volumes (2-3 mm per month), but rain still occurs regularly, approximately 8-11 days per month. Given the average monthly temperatures, precipitation throughout the year falls predominantly as rain.

When planning a trip to Karatsu, it is important to consider its coastal climate with distinct seasons and frequent precipitation throughout the year. An essential item in your suitcase will be comfortable shoes for walking around the city and its surroundings. Given that the number of rainy days is quite high every month (from 8 to 18 days), a light folding umbrella or a compact raincoat will come in handy in any season. The principle of layering your clothes is your best ally, allowing you to easily adapt to temperature changes throughout the day.

In summer, from June to August, Karatsu is warm and humid, with average temperatures rising to 26-27.5°C, and in August, they can reach nearly 30°C. This period sees the highest amount of precipitation, especially in July. It is recommended to bring light, breathable clothing made of natural fabrics (cotton, linen), shorts, T-shirts, and sandals. Don't forget sunscreen, a hat, and sunglasses. In winter, from December to February, the weather is cool, with average temperatures around 7-8°C. You will need warm clothes: sweaters, warm trousers, a jacket or coat, as well as a hat, scarf, and gloves. Waterproof outerwear will be useful due to frequent, though not always heavy, precipitation.

Spring (March–May) and autumn (September–November) in Karatsu are characterized by mild and pleasant weather, ideal for sightseeing. Average temperatures range from 11°C to 19°C in spring and from 24°C to 14°C in autumn. During these transitional seasons, a layered approach is particularly relevant: T-shirts, long-sleeved shirts, and a light jacket or fleece that can be taken off or put on depending on the weather. Evenings can be cool, so an extra layer of clothing won't hurt. And, of course, don't forget an umbrella in case of rain.