A Guide to Understanding Rainy Season in Japan

Learn when tsuyu begins and how to prepare

Ajisai (hydrangea) in full bloom in grounds of Kiyomizu Kannon Do in Ueno park, Taito. Tokyo, Kanto, Japan, North-East Asia, Asia Details Credit:
••• Ajisai (hydrangea) in full bloom in Japan. Will Robb/Getty Images

Japan is well known for its rainy season. This period is referred to as both tsuyu and baiu. If you plan to travel to the country, you should know when to expect the rainy season. Because Japan is a geographically diverse nation, made up of several islands, the rainy season may take place at slightly different times depending on the region you visit.

With this brief guide to the rainy season, learn how to prepare for this uniquely Japanese weather trend.

The Start of Rainy Season

Rainy season in Okinawa usually begins in early May. In other regions, it runs from early June through the middle of July. Hokkaido, the northernmost prefecture of Japan, actually does not have tsuyu. That doesn't mean the weather there is always perfect, however. Some parts of the prefecture experience consecutive cloudy and chilly days in the early summer that resemble tsuyu. That said, Hokkaido's weather tends to be nicer than other regions of Japan. So, if you'd rather not deal with the rainy season, that's the region to visit.

Unpredictable Weather Conditions

The weather during tsuyu is unstable, which means that it is important to prepare for rain at any time. Although this season is typically characterized by rain and lower temperatures, sometimes it doesn't rain so much, and it's hot outside. With that in mind, if you visit Japan during the rainy season, bring several different clothing options and accessories with you.

Dress in layers, so you can be prepared for unpredictable weather at all times.

The storm front often brings heavy rain in the Kyushu region. So, if you are visiting western regions, you need to be more aware of the possibility of rain.


The main problem during the rainy season is the humidity.

People tend to become irritated by it. Taking a bath or shower often helps one keep comfortable when it's clammy outside. But the humidity doesn't just affect a person's physical comfort. It also creates conditions perfect for mold to grow. It is important to avoid mold by airing out your closets or home when the sun finally does come out during the rainy season. Because many cases of food poisoning occur during this period, it's also important to be careful about what you eat and to refrigerate food promptly.

Rice Cultivation

Although tsuyu is a gloomy time, the rain is very important for rice cultivation. As you surely know, rice is a food staple, not just in Japan, but in many countries in the East. The other benefit of the rainy season is that many pretty flowers bloom during this time. One of them is ajisai (hydrangea), which is a symbol of tsuyu or baiu.

A variety of irises also blooms during this season. You can view them in many gardens and parks. It might be a good idea to hike the small mountains in your area or to walk to neighborhood parks to see more flowers. Viewing lovely plants makes the Japanese feel relaxed on gloomy days.