Because there is a lot of rain during the season when plums ripen.

The term “tsuyu” (rainy season) is said to originate from the fact that in China, around June when plums ripen, there is a lot of rainfall. The word was introduced to Japan around the Nara period. In China, it was originally written as “黴雨” (literally “mold rain”), but because the character 黴 (mold) has an unpleasant connotation, they are said to have used 梅 (plum), which is pronounced the same as the Sino-Japanese reading of 黴 (bai), instead.

the period just after the rainy season has begun

“Nyūbai” is one of the traditional seasonal markers that indicates the start of the rainy season on the calendar, typically falling around June 11 each year. Unlike the rainy season onset announced by the Japan Meteorological Agency, it is fixed by a calendar date.

Apply warm air with a hair dryer

The surface of the umbrella is treated with a fluorine-based water-repellent coating, but its effectiveness diminishes with use. However, because fluorine responds well to heat, evenly applying warm air with a hair dryer can restore its water-repellent properties.

A hemispherical shape with a flat bottom and a rounded top

In illustrations, raindrops are often drawn as teardrop-shaped, but real raindrops become hemispherical—with a rounded top and a flat bottom—because they encounter air resistance as they fall. Small raindrops are nearly spherical, while larger ones become increasingly flattened.

around August 7

At the Japan Meteorological Agency, if they cannot announce the end of the rainy season by early August (around Risshū, approximately August 7), they may designate it as “no end to the rainy season.” After Risshū, it is considered autumn on the calendar, so it is generally customary not to declare the end of the rainy season after that point.

get heavier

On humid days, hair absorbs moisture from the air, causing its weight to increase slightly. This is why hair can feel heavier and become more frizzy on rainy days. There are even data suggesting that at around 90% humidity, hair weight can increase by about 10%.

clear sunny weather in early summer (literally ‘May-clear sky’; in modern usage often refers to sunny days in June due to the lunar calendar)

Satsuki-bare refers to a term used when the rain temporarily stops during the rainy season and clear skies appear. In haiku seasonal words (kigo), it is used as a “early summer” season word, since sunny spells right after the end of the rainy season are also called satsuki-bare.