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Why is June ‘The Month of No Water’?

The literal mysteries of tsuyu, the Japanese term for the rainy season.

By 5 min read 5

The start of tsuyu, or the rainy season, has already started in Japan. I’ve always wondered how the beginning of the rainy season was determined, for no sooner is the season announced than we experience a week of beautiful, sunny weather. 

It’s as if mother nature is snubbing her nose at all the meteorologists and saying, “Think ye can pin me down, d’ye? Well, take that!” 

The answer to this question lies in first understanding why it rains. 

The baiu zensen

The tsuyu weather pattern.

From about May to July, there is a stationary front over Japan known as the baiu zensen (梅雨前線, the seasonal rain front). Check a weather map of Japan at this time of year, and you’ll find a flat front with semi-circles on the northern side and triangles on the southern side. 

This indicates a stationary front or a non-moving boundary between two differing air masses. Because of the baiu zensen, long continuous rainy periods can linger in the area affected.

In East Asia, air masses of differing temperatures and humidity from areas of high atmospheric pressure over the Sea of Okhotsk and the Pacific Ocean meet along the baiu zensen, creating clouds and rain. The strength of these two regions bumping up against each other prevents the front from dissipating.

When there have been several days of unsettled weather, and it looks likely to continue to be rainy or cloudy for several successive days, the Japanese Meteorological Agency will announce that a particular region of Japan has entered tsuyu iri (梅雨入り, the rainy season). 

Similarly, tsuyu ake (梅雨明け, the end of the rainy season) is announced when the rains have stopped, and there have been consecutive sunny days. If the past is anything to go by, the rainy season will end in the northern part of Kyushu around mid-July, or just in time for the Hakata Gion Yamakasa festival.

Plums and mold

Is it the season for umeshu?

While the mechanics of tsuyu are relatively straightforward, there are many aspects about the season that can be somewhat confusing. The first question many people have concerns the name of the season: tsuyu, quite literally, means “plum rain.” 

Why is the season called “plum rain” when Japan’s beloved ume no hana (梅の花, plum blossoms) typically bloom in February? Because (holds one theory) the rainy season coincides with the picking of said plums for making umeshu (梅酒, plum liquor) and umeboshi (梅干し, dried and pickled plums).

Another theory maintains that the original name for the season was baiu (黴雨, lit. “moldy rain”) due to the high humidity and heat creating the perfect conditions for mold to grow. 

The “moldy” half of the name, bai (黴), was replaced with the Chinese character ume (梅, plum), which could be read the same way. Lending some credence to this theory is the fact that in China, the rainy season is also written 梅雨 (though pronounced “meiyu”) and is written by some as 霉雨, where 霉 means “mold.”

Interestingly, the kanji for plum (梅) contains the radical 毎 in it, which means “every” as in “every day,” giving the word baiu (梅雨) the sense of it raining every day. In Korea, the name for the season is jangma (장마, lit. “long rain”).

Japan’s old calendar 

Rain in Harajuku.

The second question people have regarding tsuyu is the traditional name of the month in which the rainy season falls: minazuki (水無月, lit. “no water month”). It comes from Japan’s old calendar, called kyuureki (旧暦) or inreki (陰暦), which was based on the lunar cycle. June, or minazuki, was the time of the year that water was more essential to rice fields.

The kyuureki is still used today for traditional events, the marine products industry and fortune-telling. Some modern-day calendars show both dates.

A look at the Western calendar is also instructive. While September is now the ninth month of the year, the name means “seventh month.” In calendars before 1752, September was considered the seventh month, October the eighth month, November was the ninth, and so on. 

The old name for June, minazuki, is aligned more closely to the drier month of July of the former calendar.

The summer months of July (Julius Caesar) and August (Augustus Caesar) today were formerly known as Quintilis and Sextilis (the fifth and sixth months of Romulus, respectively) in the 10-month calendar of ancient Rome in which the year started in March.

The Japanese calendar experienced a similar change in the latter half of the 19th century when the tenporeki calendar, a lunisolar system used for just under 30 years from 1842 to 1872, was abandoned in favor of the Gregorian calendar. 

To make the change, the second day of the 12th month of the fifth year of Meiji (明治5年12月2日) became the first day of the first month of the sixth year of Meiji (明治6年1月1日)—so December of 1872 lasted only two days!

The month of no water

Japan needs a lot of water for its rice.

Because of the shift from a lunisolar calendar to a sun-based one, the former names of the months are sometimes off by several weeks. For example, June 7 is May 13, according to kyuureki. 

May (五月, gogatsu) is also known by its former names satsuki (五月 or 皐月, “five-month”) and samidare (五月雨, also read satsuki ame) which mean “May rain.” It is synonymous with the rainy season. 

The old name for June, minazuki (again, the month of no water), is aligned more closely to the drier month of July of the former calendar. Some believe the name may also derive from the great need for water for rice planting, which occurs during this time of the year.

If you look at June 11 on a traditional Japanese calendar, which gives both modern and kyuureki dates, you may see 入梅 (nyubai, lit. “enter + plum”). During the Edo period, the rainy season was believed to begin on or around June 11—also known as kasa no hi (傘の日, “Umbrella Day”).

So as we enter the rainy season, I offer a prayer to both Kuraokami, the dragon god of rain, and Raijin, the god of lightning, thunder and storms: May this season bring us all the rain we need and no more—and may it be over sooner rather than later.

Do you enjoy tsuyu? Do you hate tsuyu? Let us know in the comments!

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  • AonghasCrowe says:


  • Christopher Lacey says:

    A different theory about the origin of the word 水無月 – http://gogen-allguide.com/mi/minazuki.html
    The ‘無’ in 水無月 is a kanji representation of な, close in meaning to の, so it actually means ‘month of water’, in the same way that October was called 神無月, meaning ‘month of the gods’ rather than ‘month of no gods’.

    • AonghasCrowe says:

      I am familiar with that theory. Read Buddhist scriptures–don’t recommend this–and you will see that 無 was used as an “ateji”, that is for its sound rather than its meaning. Interestingly, way back in day (see Man’yōshū and Man’yōgana), Chinese characters were used both for their sound and meaning.

      Looking into Minazuki, though, I have found many practical explanations as to why the sixth month was considered the month of “no” water. They make sense, considering the shift in the calendar back in the late 1880s. (The names of the months themselves date back to the Heian Period, a thousand-plus years ago.)

      As for 神無月 (Kannazuki), it, similarly, has been interpreted as “Month of the Gods” or “Month of no Gods” because all of the gods (but one) are believed to have left for their annual vacation at Izumo.

  • AonghasCrowe says:

    Funny, but this year June truly has been the “month of no water” for us in Fukuoka. It’s been nice and sunny most days since the start of the rainy season was announced on June 6th (aka. Roll Cake Day–look it up). Last weekend, we did get some rain, but it looks like we are in for another dry spell.

    Meanwhile, the dam level in Fukuoka prefecture is down to the mid 50s, or 30 to 40 percentage points lower than where it ought to be in a typical year. Some dams have fallen to as low as 18%.

    If things don’t improve anytime soon, we may find ourselves in a serious pickle. It won’t be the first time, though. Back in the summer of ’94, one year after one of the coolest and wettest summers that caused rice shortages throughout Japan (Remember that?), we had one of the driest summers. If memory serves me correctly, water had to be rationed for over a month.

    At first water service was cut off from, I believe, 10 in the evening until 10 in the morning. In those days, I worked from about 9am to 9pm–don’t ask–meaning I had one hour to shower, do my “duty”, wash clothes, cook, and clean up. It was hell. After several weeks, water service was expanded a bit. And when a big typhoon hit, all was back to normal again. So, hurray for typhoons!

  • AonghasCrowe says:

    Title is a bit misleading. The rainy season is not called “the month of no water”. June is.



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