East Asian rainy season

Last updated
Plum rain falling on two clear umbrellas, looking up toward the Tokyo Metropolitan Government Building, in June 2009. Plum rain in Shinjuku, Tokyo.jpg
Plum rain falling on two clear umbrellas, looking up toward the Tokyo Metropolitan Government Building, in June 2009.
East Asian rainy season
Chinese name
Chinese 梅雨
Korean name
Hangul 장마 / 매우기
Hanja — / 梅雨期
Japanese name
Kanji 梅雨
Kana つゆ / ばいう

The East Asian rainy season, commonly called the plum rain (Chinese :梅雨; pinyin :méiyǔ), 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 in East Asia between mainland China, Taiwan, Korea, Japan and the Russian Far East. The wet season ends during the summer when the subtropical ridge becomes strong enough to push this front north of the region. These weather systems can produce heavy rainfall and flooding.



The term "plum rain" was a Chinese term for the rain in the fourth and fifth lunar month. [1] [2] It specifically refers to the historical belief that, when the plums turn yellow and fall at the south of the Yangtze in the fourth and fifth months, the moisture that evaporates from the plant turns into rain. [2]

The term appears in the following poem by Du Fu (fl. 8th century) of the Tang dynasty:


Plum rain
On the Xipu road from the Southern Capital (present-day Chengdu),
the fourth month ripens the yellow p[r]unus.
The long river goes off surging,
and, darkening, a fine rain comes.
Roof-thatch, loosely bound, is easily soaked,
clouds and fog are dense and will not lift.
All day long the dragons delight,
whirlpools turning with the bank. [1]


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. [3] The rainy season usually lasts from May to June in Taiwan and Okinawa, [4] from June to July (approximately 50 days) in Russian Primorsky Krai, Japan and Korea and from July to August in eastern China (especially the Yangtze and Huai River regions).

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 precipitation to Primorsky Krai, Japan, Korea, eastern China, and Taiwan. As the front moves back and forth depending on the strength of cool and warm air masses, there is often prolonged precipitation and sometimes flooding in eastern China. However, in the years that it does not rain as much as usual, a drought might result. The rainy season ends when the warm air mass associated with the subtropical ridge is strong enough to push the front north and away.


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. The most rain in a one-hour period as recorded in Japan was in Nagasaki in 1982 with 153 millimetres (6.0 in). The highest overall recorded rainfall during the rainy season in Japan was in 2003 when Miyazaki Prefecture recorded rains of 8,670 millimetres (341 in).


In Japan, the rainy season is called tsuyu (梅雨), and lasts from early June to mid-July in the most of the country (Honshu, Kyushu and Shikoku), approximately June 7 to July 20 in the Kansai and Kantō regions in Honshū. [5] The tsuyu season is roughly a month earlier (early May through mid-June) in Okinawa (the southernmost region of the country). There is no pronounced tsuyu season in Hokkaidō (the northernmost region of the country) because the tsuyu front usually attenuates before it reaches the region so that it cannot produce the abundant rainfall. Tsuyu is also known as Samidare (五月雨, literally "the fifth-month rain (in the Japanese traditional calendar)", roughly corresponding to June in the modern calendar). The pop artist Eiichi Ohtaki produced a popular song by this name, and a WW2 Japanese naval ship was also given this name.

The rains in the middle of November - early December are sometimes called the sazanka tsuyu, literally "rainy season of the camellia" on account of the timing with the blossoming of the seasonal flower.

This period is generally avoided for tourism, but some sights are considered particularly atmospheric in the rain and fog, particularly mountain forests, notably Sacred Sites and Pilgrimage Routes in the Kii Mountain Range (including Mount Kōya). [5] Vegetation, especially moss, is also rather lush at this time, and hence sights known for their moss, such as Saihō-ji (the moss temple) are also popular at this time of year.[ citation needed ]


The rainy season is between June and mid-July. It is caused by hot and humid high pressure forming in the Sea of Okhotsk due to the North Pacific anticyclone combining with Asiatic continental high pressure. When the two meteorological events meet they form a long jangmajeonseon (Korean : 장마전선). Beginning in late-May, the North Pacific high pressure forces the weaker continental anticyclone south of Okinawa Island. This fall to the south then reverses and gradually strengthens as it moves northwards back towards the Korean peninsula. On landfall, heavy monsoon rains lead to torrential downpours and flooding. By August the system has weakened as the southern systems retreat towards the Filipino archipelago.

By early autumn, the North Pacific high-pressure system is pushed away as Asiatic continental cold high pressure moves southwards. This produces inclement weather although not on the scale of the summer monsoons. Korea can, however, be struck by typhoons during this period.


In some years, the rainy season's actual beginning and end are under debate. For example, in 2005, the subtropical ridge moved quickly northward in late June/early July. The weather front skipped the Chang Jiang region and there was no rainy season there. Then, the ridge retreated southward and there was significant rainfall in the region. This gave rise to the question of whether this was the summer-type rainfall pattern that is common after the first rainy season or the second rainy season. Some meteorologists even argued that the rainy period in late June was not a true rainy season. [6] [7] [8] [9] [10]

See also

Related Research Articles

Monsoon Seasonal changes in atmospheric circulation and precipitation associated with the Intertropical Convergence Zone moving

A monsoon is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscillation of the Intertropical Convergence Zone between its limits to the north and south of the equator. Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry phase. The term is also sometimes used to describe locally heavy but short-term rains.

<i>Prunus mume</i> East Asian tree species

Prunus mume is an East Asian and Southeast Asian tree species classified in the Armeniaca section of the genus Prunus subgenus Prunus. Its common names include Chinese plum,Japanese plum, and Japanese apricot. The flower, long a beloved subject in the traditional painting and poetry of East Asia and Vietnam, is usually called plum blossom. This distinct tree species is related to both the plum and apricot trees. Although generally referred to as a plum in English, it is more closely related to the apricot. In East Asian cuisine and Vietnamese cuisine (Vietnamese), the fruit of the tree is used in juices, as a flavouring for alcohol, as a pickle and in sauces. It is also used in traditional medicine.

1956 Pacific typhoon season

The 1956 Pacific typhoon season has no official bounds; it ran year-round in 1956, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.

The East Asian Monsoon is a monsoonal flow that carries moist air from the Indian Ocean and Pacific Ocean to East Asia. It affects approximately one-third of the global population, influencing the climate of Japan, the Korean Peninsula, Taiwan, and much of China. It is driven by temperature differences between the East Asian continent and the Pacific Ocean. The East Asian monsoon is divided into a warm and wet summer monsoon and a cold and dry winter monsoon. This cold and dry winter monsoon is responsible for the aeolian dust deposition and pedogenesis that resulted in the creation of the Loess Plateau. The monsoon influences weather patterns as far north as Siberia, causing wet summers that contrast with the cold and dry winters caused by the Siberian High, which counterbalances the monsoon's effect on northerly latitudes.

Typhoon Morakot Pacific typhoon in 2009

Typhoon Morakot, known in the Philippines as Typhoon Kiko, was the deadliest typhoon to impact Taiwan in recorded history. The eighth named storm and fourth typhoon of the 2009 Pacific typhoon season, Morakot wrought catastrophic damage in Taiwan, leaving 673 people dead and 26 missing, and causing roughly NT$110 billion (US$3.3 billion) in damages. Morakot originated as a tropical depression in the West Pacific on August 2. The system initially moved northeastward, before taking a westward track, developing into a tropical storm on August 3, with the JMA giving it the name Morakot. The storm gradually strengthened as it moved towards Taiwan, intensifying into a Category 1-equivalent typhoon on August 5. Morakot reached its peak intensity on August 7, with a minimum central pressure of 945 millibars (27.9 inHg), maximum 10-minute sustained winds of 140 km/h (85 mph), and maximum 1-minute sustained winds of 150 km/h (90 mph). Afterward, Morakot's forward motion slowed and the system gradually weakened, making landfall on central Taiwan later that day as a severe tropical storm. Over the next day, Morakot slowly meandered over Taiwan, before emerging into the Taiwan Strait and turning northward, making landfall on Mainland China on August 9. Afterward, Morakot accelerated northward while gradually weakening, before later turning northeastward. On August 11, Morakot degenerated into a remnant low in the East China Sea, before dissipating on August 13, over northern Japan.

Climate of Asia Overview of the climate of Asia

The climate of Asia is dry across its southwestern region, with dry across much of the interior. Some of the largest daily temperature ranges on Earth occur in the western part of Asia. The monsoon circulation dominates across the southern and eastern regions, due to the Himalayas forcing the formation of a thermal low which draws in moisture during the summer. The southwestern region of the continent experiences low relief as a result of the subtropical high pressure belt; they are hot in summer, warm to cool in winter, and may snow at higher altitudes. Siberia is one of the coldest places in the Northern Hemisphere, and can act as a source of arctic air mass for North America. The most active place on Earth for tropical cyclone activity lies northeast of the Philippines and south of Japan, and the phase of the El Nino-Southern Oscillation modulates where in Asia landfall is more likely to occur.

Typhoon Rammasun (2002) Category 3 Pacific typhoon in 2002

Typhoon Rammasun, known in the Philippines as Typhoon Florita, was the first of four typhoons to contribute to heavy rainfall and deadly flooding in the Philippines in July 2002. The fifth tropical cyclone of the 2002 Pacific typhoon season, Rammasun developed around the same time as Typhoon Chataan, only further to the west. The storm tracked northwestward toward Taiwan, and on July 2 it attained its peak intensity with winds of 160 km/h (100 mph). Rammasun turned northward, passing east of Taiwan and China. In Taiwan, the outer rainbands dropped rainfall that alleviated drought conditions. In China, the rainfall occurred after previously wet conditions, resulting in additional flooding, although damage was less than expected; there was about $85 million in crop and fishery damage in one province.

Tropical Storm Nakri (2014) 2014 Pacific Ocean typhoon

Tropical Storm Nakri, known in the Philippines as Tropical Storm Inday, was a large, long-lived, and slow-moving tropical cyclone that produced prolific rains over Japan and South Korea in early August 2014.

Meiyu front Weather system

The meiyu front, also known as baiu front, is a persistent nearly stationary weak baroclinic zone in the lower troposphere. It is located over the east coast of China and Taiwan at its western end, and over the Pacific Ocean south of Japan at its eastern end.

July 2016 North China cyclone

The July 2016 North China cyclone was a devastating extratropical cyclone which produced torrential precipitation and caused widespread flash floods over North China and portions of nearby regions, resulting in at least 184 deaths and ¥33.19 billion of damage in China.

Shimoshima Island, Amakusa

Shimoshima is the largest island in the Amakusa archipelago. Its coasts are washed by Ariake Sea, Amakusa-nada sea, East China Sea and Yatsushiro Sea. Most of Shimoshima Island is administered as part of Amakusa city, with 67 km2 patch on north-west coast belonging to Reihoku town. The island's highest peak is Mount Tenjiku 538.4 m (1,766 ft).

Kamishima Island, Amakusa

Kamishima is the second largest island in the Amakusa archipelago. Its coasts are washed by Yatsushiro Sea and Shimabara Bay of Ariake Sea, both being the part of East China Sea. The western part of Kamishima Island is administered as part of Amakusa city, while eastern part is administered as part of Kami-Amakusa city. The island's highest peak is Mount Kuratake 682 m (2,238 ft).

Hirado Island Island in Nagasaki, Japan

Hirado Island is the 4th largest island in the Nagasaki prefecture. Its coasts are washed by East China Sea. The entire island and the part of the nearby Kyushu mainland is administered as part of Hirado city. The island's highest peak is Mount Yasumandake 535 m (1,755 ft). The Saikai National Park comprise 24% of the island's total area.

Nagashima Island, Kagoshima

Nagashima is the largest island in the island chain south of Shimoshima Island, Amakusa. Its coasts are washed by Yatsuhiro Sea, Hachimannoseto strait and East China Sea. Nagashima Island, together with Shishi-jima, Shoura Island and Ikara islands, has been administered as part of Nagashima town since 2006. The island's highest peak is Mount Dainaka-dake 403 m (1,322 ft), although Mount Yatake is only slightly lower at 402 m (1,319 ft)


Ōyano-jima (南大東島), also spelt as Ōyanojima It is administered as part of the city of Kami-Amakusa. It is connected to the Japanese mainland cince 1966 by Five Bridges of Amakusa. The Japan National Route 266 passes through the island. The island primary industry is aquaculture of fish and shrimps. Large part of island belongs to Unzen-Amakusa National Park.

Typhoon Kong-rey (2018) Pacific typhoon in 2018

Typhoon Kong-rey, known in the Philippines as Typhoon Queenie, was a large and powerful typhoon that was tied with Typhoon Yutu as the most powerful tropical cyclone worldwide in 2018. The twenty-fifth tropical storm, eleventh typhoon and 6th super typhoon of the 2018 Pacific typhoon season, Kong-rey originated from a tropical disturbance in the open Pacific. For a couple days, it went westward, organizing into a tropical depression on September 27. Then it intensified into a powerful Category 5 super typhoon early on October 2. Kong-rey underwent an eyewall replacement cycle after its peak intensity, causing it to weaken into a Category 3 typhoon under unfavorable conditions. Kong-rey then struck South Korea on October 6 as a tropical storm. Kong-rey transitioned into an extratropical cyclone later that day while impacting Japan.

Typhoon Lekima Pacific typhoon in 2019

Typhoon Lekima, known in the Philippines as Typhoon Hanna, was the costliest typhoon in Chinese history. The ninth named storm of the 2019 Pacific typhoon season, Lekima originated from a tropical depression that formed east of the Philippines on July 30. It gradually organized, became a tropical storm, and was named on August 4. Lekima intensified under favorable environmental conditions and peaked as a Category 4–equivalent Super typhoon. However, an eyewall replacement cycle caused the typhoon to weaken before it made landfall in Zhejiang late on August 9, as a Category 2–equivalent typhoon. Lekima weakened subsequently while moving across Eastern China, and made its second landfall in Shandong on August 11.

2020 Kyushu floods

The 2020 Kyushu floods were a series of floods in July 2020 brought on when record-breaking heavy rain hit the prefectures of Kumamoto and Kagoshima, on the southern Japanese island of Kyushu, on 4 July 2020 in the middle of the East Asian rainy season. The event is officially referred to as Reiwa ni-nen shichi-gatsu gōu by the Japan Meteorological Agency. As a result of flooding and landslides, 77 people were confirmed dead and approximately seven are missing. Fourteen of the victims were residents of an old age home in Kuma, Kumamoto that was flooded. Approximately 15,335 buildings were destroyed, damaged or flooded.

Typhoon Songda (2011) Pacific typhoon in 2011

Typhoon Songda, known in the Philippines as Typhoon Chedeng, was an exceptionally strong and catastrophic typhoon that lashed the eastern coast of the Philippines as a Category 5–equivalent super typhoon and affected the nearby Taiwan and Japan as a weakening tropical cyclone. The fourth tropical depression, second named storm and the first super typhoon of the 2011 Pacific typhoon season, Songda formed from a non-tropical low that was embedded from the Intertropical Convergence Zone on May 17. An area of low-pressure subsequently formed and became organized for the JTWC to issue a TCFA on the system and the JMA to issue advisories, before both agencies declared it a tropical storm, earning the name Songda. Under favorable conditions, Songda slowly intensified as it entered the Philippine Area of Responsibility, with the PAGASA naming it Chedeng on May 23. On the next day, the three agencies declared the system a typhoon before rapidly intensifying to a super typhoon over the Philippine Sea. As it entered an unfavorable environment for further strengthening, Songda slowly weakened as it passed near Taiwan, before becoming extratropical near Japan. The remnants of the system slowly moved to the northeast, before absorbing to another extratropical cyclone to the south of Alaska.

Typhoon In-fa Pacific typhoon in 2021

Typhoon In-fa, known in the Philippines as Typhoon Fabian, was a very large and costly tropical cyclone that brought record amounts of rainfall to China in July 2021, becoming the second-wettest tropical cyclone ever recorded in the country. It was also the first storm to impact the city of Shanghai since Typhoon Mitag of 2019. The ninth depression, sixth tropical storm and third typhoon of the 2021 Pacific typhoon season, the system was first noted by the Joint Typhoon Warning Center as an area of low pressure, located east of the Philippines on July 14. Favorable conditions helped the storm to intensify, becoming a tropical depression, two days later and a tropical storm on July 17, being assigned the name In-fa by the Japan Meteorological Agency. Located in a weak steering environment, the system struggled to organize under dry air and moderate wind shear before organizing further. It continued to move mostly westward, strengthening into a typhoon and deepening quickly. The storm struggled to organize itself significantly due to continuous dry air intrusions and its frequent motion changes. On July 21, it reached its peak intensity according to the JTWC with winds of 175 km/h (110 mph); the JMA estimated a lower numbers of 150 km/h (90 mph) on the system. Nevertheless, the system reached its minimum barometric pressure of 950 hPa (28.05 inHg), three days later after passing through the Ryukyu's. As it entered the East China Sea, marginal conditions started to take toll on the system, with In-fa weakening steadily and slowly until it made its consecutive landfalls over Putuo District of Zhoushan and Pinghu from July 25 and 26, respectively as tropical storms.


  1. 1 2 Owen, Stephen [translator & editor], Warner, Ding Xiang [editor], Kroll, Paul [editor] (2016). The Poetry of Du Fu Open Access logo PLoS transparent.svg , Volume 2. De Gruyter Mouton. Pages 298–299. ISBN   978-1-5015-0189-0
  2. 1 2 Lu Dian's Piya (published in the Song dynasty). Cited in Sargent, Stuart Howard (2007). The Poetry of He Zhu (1052-1125): Genres, Contexts, and Creativity . Brill. p.  18. ISBN   978-90-04-15711-8.
  3. Archived 2006-04-27 at the Wayback Machine
  4. "Okinawa Travel Information". Archived from the original on 2013-03-10. Retrieved 2011-05-13.
  5. 1 2 Rainy Season (Tsuyu), japan-guide.com
  6. 入梅不像梅出梅梅更浓 梅雨"变味"真假难辨 (in Chinese). Xinhuanet. 2005-07-14. Archived from the original on 2011-07-18. Retrieved 2008-05-07.
  7. 倒黄梅?二度梅? 有关专家认为再下就要变成梅雨 (in Chinese). Sina. 2005-07-09. Retrieved 2008-05-07.
  8. 是"倒黄梅"还是"二度梅"?接连阴雨让专家直挠头 (in Chinese). Sina. 2005-07-08. Retrieved 2008-05-07.
  9. 上海是否出现了"倒黄梅"?为啥视而不见 (in Chinese). CNHYC. 2005-07-17. Archived from the original on 2007-03-11. Retrieved 2008-05-07.
  10. 是倒黄梅还是二度梅? (in Chinese). 新华报业网. 2005-07-12. Archived from the original on 2008-05-25. Retrieved 2008-05-07.