What is tsuyu, and why does everyone talk about the weather so much in June?
From roughly early June to mid-July (varies by region), much of Japan enters tsuyu: weeks of high humidity and frequent rain. Shops sell dehumidifiers, mold sprays, and plastic umbrella-bag stands appear at entrances.
Tsuyu is a period of continuing rain and humidity caused by a stationary front. It strongly affects everyday life, including laundry, mold prevention, and how umbrellas are handled.
Why — five layers
Warm, humid air meets cold air and forms the stationary baiu front near Japan. Its influence brings consecutive rainy days and high humidity.
The Japan Meteorological Agency announces the beginning and end of tsuyu for each region. Every year, these announcements receive extensive news and weather coverage.
Because rain and humidity affect daily life during tsuyu, the weather becomes a common topic of conversation. On trains and in shops, people also take care not to wet others or their belongings with damp umbrellas.
International view
Many parts of Asia have a rainy season, but in Japan the beginning and end of tsuyu are officially announced, and products and daily habits tailored to it are widespread.
But not always
Hokkaido has no ordinary tsuyu, though stretches of rainy or cloudy weather may be called Ezo-tsuyu. Some years also bring a “dry tsuyu” with little rain even during the season.
What to do
Check the forecast during tsuyu. Use umbrella bags or stands when entering shops, and ventilate or dehumidify rooms to prevent mold on clothes and shoes.
Sources
- Japan Meteorological Agency tsuyu announcements
- baiu front meteorology
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