Tanegashima Climate

Tanegashima has a humid subtropical climate (Köppen climate classification Cfa) with very warm summers and mild winters. The temperatures vary only a little between day and night from about April until October. From about November until March, the difference in daytime and nighttime temperatures becomes very noticeable. What might be a tee shirt afternoon can quickly become a heavy coat, with a knit hat and gloves, night.
Monthly Data

Precipitation is high throughout the year, but is highest in the months of May, June, and September. Some of this can be attributed to typhoons, especially towards the end of Summer, but the island is subject to torrential rains throughout the year. During periods of very heavy rain it is best to stay off the roads, which often become impassable. Equally important is to stay away from the rivers, which although small, can turn into fast moving rapids during a mega rain event.
Rainy Season

The East Asian rainy season, commonly called the plum rain, Japanese: 梅雨, tsuyu, is caused by precipitation along a persistent stationary front known as the Meiyu front for nearly two months during the late spring and early summer between eastern Russia, China, Taiwan, Korea, and Japan. The wet season ends during the summer when the subtropical ridge becomes strong enough to push this front north of the region.

An east-west zone of disturbed weather during spring along this front stretches from the east China coast, initially across Taiwan and Okinawa, later, when it has shifted to the north, eastward into the southern peninsula of South Korea and Japan. The rainy season usually lasts from May to June in Okinawa and from June to July (approximately 50 days) in the main islands of Japan.

The weather front forms when the moist air over the Pacific meets the cooler continental air mass. The front and the formation of frontal depressions along it brings copious amounts of precipitation to Japan. The rainy season ends when the warm air mass associated with the subtropical ridge is strong enough to push the front north and away.

In Japan, the season lasts from early June to mid-July for most of the country (on the main island of Honshū and the islands of Kyūshū and Shikoku), approximately June 7 to July 20 for the main Kansai and Kantō regions. It comes a month earlier to Okinawa in the south (early May through mid-June), but Hokkaidō in the north is largely unaffected.

The high humidity in the air during this season encourages the formation of mold and rot not only on food but on fabrics as well. Environmentally, heavy rains encourage mudslides and flooding in all areas affected.

This period is generally avoided for tourism and for good reason.
Strong Typhoons

Hey talk to any of the locals and they insist this island rarely sees a typhoon....yeah right. The island usually will get a couple of strong tropical storms and at lease one strong typhoon, with category 2 storms becoming more frequent as global warming continues.

The best advice is to stay away from rivers and the beaches during a typhoon due to high amounts of rain and storm surge. In addition, better to not be too close to any structures. Tanegashima has plenty of really old buildings which are ready to be blown over by the next visiting typhoon.
Table saffi simpson hurricane wind scale and storm typeSaffir-Simpson Scale

This table shows the hurricane and typhoon categories used to classify the intensity of storms.
Typhoon vongfong 2014 october 12 tropical storm map trackFrequent Typhoons

Yup, typhoons hit this island a lot more often than the locals want to admit. Check out the following Wikipedia pages to see for yourself. The list begins at 2014 which is the year we moved to the island and within a month watched a tropical storm and a typhoon wreak havoc on Tanegashima within a week of each other.
Wikipedia: 2021 Pacific typhoon season
Wikipedia: 2020 Pacific typhoon season
Wikipedia: 2019 Pacific typhoon season
Wikipedia: 2018 Pacific typhoon season
Wikipedia: 2017 Pacific typhoon season
Wikipedia: 2016 Pacific typhoon season
Wikipedia: 2015 Pacific typhoon season
Wikipedia: 2014 Pacific typhoon season
Additional Information