CLIMATE IN JAPAN: WEATHER, OCEAN CURRENTS, YELLOW DUST

CLIMATE OF JAPAN

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Spring cherry trees in Yoshino Most of Japan has four distinct seasons, which are somewhat similar to those in the United States. The Japanese climate is generally mild thanks to the tempering effect of the ocean. But because the islands of Japan stretch 2,250 kilometers (1,400 miles) from north to south there are great variations, ranging from tropical in Okinawa (with the same latitude with Key West, Florida) to blustery and snowy in Hokkaido, the northernmost main island of Japan (with the same latitude as Quebec). Tokyo is at about 36 north latitude, comparable to that of Tehran, Athens, or Los Angeles

Japan is generally a rainy country with high humidity, ranging from 50 percent to 75 percent. Temperature extremes are less pronounced than in the United States, but the climate varies considerably seasonally as well as regionally. Sapporo, on Hokkaido, has warm summers and long, cold winters with heavy snowfall. Temperatures can drop below −30°C (-22°F). Summer temperatures sometimes exceed 35°C (95°F). Tokyo, Nagoya, Kyoto, Osaka, and Kobe, in central and western parts of the largest island of Honshu, experience relatively mild winters with little or no snowfall and hot, humid summers. Fukuoka, on the island of Kyushu, has a climate similar to that of Washington, DC, with mild winters and long, hot, humid summers . Okinawa is subtropical. Climate also varies with altitude and with location on the Pacific Ocean or on the Sea of Japan. and mild winters.

A major feature of Japan’s climate is the clear-cut temperature changes between the four seasons. Rainfall is abundant. Japan is subject to typhoons in the late spring, summer and fall. In Tokyo summer is hot and humid (25.2°C, 77.4°F), autumn is comfortable (17.6°C, 63.7°F), winter is cold, sunny and dry with occasional light snowfalls (5.2°C, 41.4°F) and spring is mild with scattered showers (14.1°C, 57.4°F). Mid-June to mid-July is the rainy season.

El Niño causes a wet summer and prolonged monsoons in Japan. During the La Niña Japan is cooler. The El Niño of 1997-98 caused typhoons in Japan. There were fears it was push snow away from Nagano and cause the 1998 Olympics to be a dismal failure. The typhoon season runs from May through October, and each year several storms usually sweep through the islands, often accompanied by high winds and heavy rains. In September 2005, Typhoon Nabi hit southern Japan causing the deaths of at least 77 people and temporarily displacing more than 300,000.

Japan gets its share of strange weather. In June 2009, there were reports of fish, tadpoles and frogs falling from the sky and landing in parking lots in four cities in Ishikawa Prefecture. Some think that the creatures were picked up by a tornado-like weather formation and dropped on the land but most think the animals fell from the bills of birds like herons that were taking the frogs and tadpoles back to their nests to feed their young. After media coverage tadpoles were spotted all across the country. Ornithologists said they didn’t think the phenomena was caused by birds.

Websites and Resources

climate map of Japan

Good Websites and Sources on Climate and Weather: Japan Meteorological Agency Japan Meteorological Agency ;Good Photos of the Seasons at Japan-Photo Archive japan-photo.de ; Statistical Handbook of Japan Land and Weather Chapter stat.go.jp/english/data/handbook ; 2010 Edition stat.go.jp/english/data/nenkan ; News stat.go.jp Weather Underground wunderground.com/global/JP ; Weather Channel Weather Channel ;World Climate World Climate ; Accuweather Accuweather ; Climate Data climatetemp.info/japan ;Wikipedia article on Geography of Japan Wikipedia ;

Good Websites and Sources of Storms in Japan: Weather Warnings from Japan Meteorological Agency jma.go.jp/en/warn ; Wikipedia article on Snow Country in Japan Wikipedia ;; BBC Picture Gallery of Flood in Japan news.bbc.co.uk ; BBC report on 2006 Tornado bbc.co.uk Video of Typhoon Surfing in Japan YouTube ; Good Japan Times article on Typhoons in Japan search.japantimes.co.jp ; Ise-Wan Typhoon Wikipedia article on the 1959 Ise-wan Typhoon (Typhoon Vera) wikipedia.org/wiki/Typhoon_Vera ; U.S. Navy Report on the 1959 Ise-wan Typhoon pdf file usno.navy.mil

Typhoons: and Hurricanes Typhoon and Hurricane Basics aoml.noaa.gov ; Data and Images from Pacific Typhoons eorc.jaxa.jp/ADEOS ; Video from Nasty Typhoon in Taiwan YouTube ; Typhoon Video YouTube ; Wikipedia article on Tropical Cyclones Wikipedia ; National Hurricane Center at the National Weather Service nhc.noaa.gov Digital Typhoon Information from the and United States Navy agora.ex.nii.ac.jp/digital-typhoon ;

Weather Patterns in Japan

From north to south, Japan covers a range of latitude of some 25 degrees and its climate is influenced by seasonal winds blowing from Siberia in the winter, by seasonal winds blowing from the Pacific Ocean in the summer and is shaped by the Asian-Pacific monsoon cycles, which bring heavy rains from the Pacific during the summer and fall, followed by icy winds from North Asia during the winter that dump snow in the mountains. [Source: Theodore C. Bestor, Countries and Their Cultures, Gale Group Inc., 2001]

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autumn in Nagano Two primary factors influence Japan's climate: a location near the Asian continent and the existence of major oceanic currents. The climate from June to September is marked by hot, wet weather brought by tropical airflows from the Pacific Ocean and Southeast Asia. These airflows are full of moisture and deposit substantial amounts of rain when they reach land. There is a marked rainy season, beginning in early June and continuing for about a month. It is followed by hot, sticky weather. Five or six typhoons pass over or near Japan every year from early August to early September, sometimes resulting in significant damage. Annual precipitation, which averages between 100 and 200 centimeters (39 to 78 inches), is concentrated in the period between June and September. In fact, 70 to 80 percent of the annual precipitation falls during this period. In winter, a high-pressure area develops over Siberia, and a low-pressure area develops over the northern Pacific Ocean. The result is a flow of cold air eastward across Japan that brings freezing temperatures and heavy snowfalls to the central mountain ranges facing the Sea of Japan, but clear skies to areas fronting on the Pacific. [Source: Library of Congress, 1994 *]

In spite of its rather small area, Japan is characterized by four different climatic patterns. Hokkaido, with a subarctic weather pattern, has a yearly average temperature of eight degrees centigrade and receives an average annual precipitation of 1,150 millimeters. The Pacific Ocean side of Japan, from the Tohoku region of northern Honshu to Kyushu, belongs to the temperate zone, and its summers are hot, influenced by seasonal winds from the Pacific. The side of the country which faces the Sea of Japan has a climate with much rain and snow, produced when cold, moisture-bearing seasonal winds from the continent are stopped in their advance by the Central Alps and other mountains which run along Japan’s center like a backbone. The southwestern islands of Okinawa Prefecture belong to the subtropical climate zone and have a yearly average temperate of over 22 degrees, while receiving over 2,000 millimeters of precipitation. [Source: Web-Japan, Ministry of Foreign Affairs, Japan]

On the summer solstice the sun rises just before 4:30am in Tokyo and reaches a zenith of 78 degrees above the southern horizon at 11:40am and sets around 7:00am. In Sapporo in northern Japan the sun reaches a zenith of 59 degrees on the summer solstice. In the southern Ryukyu Islands just north of the Tropic of Cancer in southern Japan the sun reached a zenith of 89 degrees.

Ocean Currents and Japanese Weather

Two major ocean currents affect this climatic pattern: the warm Kuroshio Current (Black Current, Japan Current); and the cold Oyashio Current (Parent Current, Chishima Current or Okhotsk Current). The warm Kuroshio Current flows northward on the Pacific side of Japan and warms areas as far north as Tokyo; a small branch, the Tsushima Current, flows up the Sea of Japan s along the west side of Japan.

From the north, the cold Oyashio current flows south along Japan’s east coast, and a branch of it, called the Liman Current, enters the Sea of Japan from the north. The Oyashio Current abounds in plankton beneficial to coldwater fish,. Its cold water cool adjacent coastal areas. The mixing of these warm and cold currents helps produce abundant fish resources in waters near Japan. The meeting point of these currents at 36 north latitude is a bountiful fishing ground. [Source: Library of Congress, 1994; Web-Japan, Ministry of Foreign Affairs, Japan]

Kevin Short wrote in the Daily Yomiuri, “About 12,000 years ago...the global climate began warming, and the strength of the warm Kuroshio, or Japan Current increased. This current, the western Pacific equivalent of the Gulf Stream, sweeps northward out of Southeast Asian, running up the Ryukyu Islands then twisting clockwise along the Pacific Ocean coasts of Kyushu, Shikoku and Honshu before heading out to sea.” [Source: Kevin Short, Daily Yomiuri, November 11, 2010]

“About 8,000 years ago, the Kuroshio became so powerful that a branch current broke off and smashed through the gap between Japan and the Korean Peninsula. This great river of warm water, called the Tsushima Current, now flows northeastward through the Sea of Japan as far as western Hokkaido and the southern tip of Sakhalin.”

“The creation of the Tsushima Current was a momentous event that radically altered Japan's climate and vegetation. The dry, cold winter winds blowing across the Sea of Japan from Siberia now pick up moisture evaporated from the warm waters, which they then deposit as heavy snow all along the north and west facing flanks of Japan's mountain ranges. As the climate grew milder and wetter, the islands' grasslands gave way to the great tracts of dense forest we see today.”

Seasons in Japan

The four seasons of Japan are 1) Winter (December-February), 2) Spring (March-May), 3 Summer (June-August) and Autumn (September-November.) The average annual temperature is 15° C 59° F) with a winter range of -9° to 16° C (15° to 61° F) and a summer range of 20° to 28° C (68° to 82°). [Source: Geo-Data: The World Geographical Encyclopedia, Gale Group Inc., 2003]

The seasons and foods are often linked together. May is associated with the new rice crop and October is associated with the rice harvest. The Springs is ushered in by plum blossoms in March and cherry blossoms in April, and is pleasant and sometimes rainy. Autumn begins in September and is characterized by falling leaves, crisp, cool, days and rice harvests. Northern Japan and temples with maple trres have pretty autumn colors. Winter tends to be mild on the Pacific side, with many sunny days, while the Japan Sea side tends to be colder and more overcast.

Winter in Hokkaido and northern Honshu are shaped by frigid northwest winds from Siberia, which occasionally sweep across from the Asian continent bringing snow to coastal regions facing the Sea of Japan and to the central mountain regions. Hokkaido, northern Honshu and the mountains in the interior of Honshu are among the snowiest places on earth.

More Frequent Extreme Weather in Japan?

In January 2012, the Yomiuri Shimbun reported: “Japan witnessed weather irregularities in the summer of 2012. Typhoon No. 12 registered the largest rainfall on record, and Typhoon No. 15 saw evacuation recommendations issued to as many as 1.22 million people in Aichi Prefecture and elsewhere. According to statistics from the Meteorological Agency, heavy rain in Japan has been on the rise over the past 100 years or so. Although the cause behind the increased rainfall remains unknown, some scientists believe it may be linked to global human activities. [Source: Yomiuri Shimbun, January 18, 2012]

“As Masahide Kimoto, vice director of the University of Tokyo's Atmosphere and Ocean Research Institute, puts it: "As the earth's climate changes, antidisaster preparations should be thoroughly reviewed, starting with city planning. Conventional wisdom can no longer cope with the situation.”

“In the case of extreme weather conditions, experts have said preventative measures have limits. Recently, a Land, Infrastructure, Transport and Tourism Ministry council discussed transitioning away from conventional thinking that aims to prevent flooding in all rivers. The council also said it would be difficult to prevent all damage in the event of future, harsher disasters.

Yellow Dust from China in Japan

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dust from a Gobi storm heading towards Japan Yellow dust from Gobi deserts and other deserts in western and north-central China and Mongolia blows into Korea and Japan. The seasonal winds that bring the yellow dust are called “Huwangsa” (yellow sand). Some of the dust and sand is the same yellow dust and sand that gives the Yellow River its color.

The yellow sand and dust dirties windshields and laundry and can cause respiratory problems. Some Japanese suffer from red, itchy eyes and runny noses and other allergy-like symptoms in the yellow sand season. Doctors the sand does not cause allergy but rather exaggerates symptoms.

Between 1980 and 1999 there was only one year in which yellow sand particles were observed on more than 40 days. But since 2000 — apart from 2003 and 2004 — yellow sand particles have been observed on more than 40 days every years, reaching 55 days in 2002. In the mid 2000s, the sand started appearing more in northern Japan and Hokkaido. Record amounts yellow sand from China and Mongolia hit Japan in the spring of 2006. Yellow sand hit Tokyo in April for the first time in six years.

Much of the yellow sand and dust originates in Gobi Desert and Ocher Plateau in China and Mongolia. After the snow thaws there the sand and dust is exposed and picked by strong spring winds that lift up the sand and dust to several thousand meters, where it is carried by westerly winds to Japan. On Mt. Fuji there is a device that measures yellow sand, dust and soot carried on winds from China.

Weather Technology of Japan

In Tokyo, the number of days with temperatures falling below freezing has increased in recent years. But this not because temperatures are lower but because the place where weather measurements are taken was moved to a colder place in a park (rather than the previous place surrounded by buildings) in December 2014.

In the 2000s, it was reported that the Japanese government was having a hard time coming up with the funds to construct new weather satellites and could be caught short without satellites when the current satellites stop working. This is no longer an issue. Japan has fully funded its next-generation geostationary weather satellites to ensure uninterrupted service.The Japan Meteorological Agency (JMA) already awarded a manufacturing contract to Mitsubishi Electric for Himawari-10. Himawari-10 is slated for launch around the Japanese fiscal year 2030. It will be equipped with advanced imagers and hyperspectral infrared sounders to track hazardous precipitation.Seamless Redundancy: JMA currently operates Himawari-9. The system uses a twin-satellite strategy (one operational, one active standby) to prevent any gap in data collection prior to the next launch

The National Research Center for Disaster Prevention (NRCDP) has a corrugated-steel Rainfall Simulator, mounted on railroad tracks, that can produce anything from drizzle to a typhoon. This devise is rolled on to artificial hills to get a sense of when dangerous mudslides begin.

Cloud Seeding in Japan

In August 2013, the Tokyo metropolitan government operated its cloud-seeding equipment for the first time in 12 years in an effort to increase rainfall and replenish water supplies. The action was taken after water levels in reservoirs serving the Tokyo region had fallen below normal following a period of dry weather. [Source: Kyodo, August 21, 2013]

Two cloud-seeding machines located near the Ogouchi Dam area in western Tokyo and neighboring Yamanashi Prefecture were activated. The system dispersed silver iodide mixed with acetone into the atmosphere. The particles were intended to act as condensation nuclei within clouds at altitudes of about 4,000 to 5,000 meters (13,000 to 16,400 feet), encouraging the formation of rain.

Several hours after the operation, rainfall of about 10 millimeters (0.4 inches) was recorded upstream of the Ogouchi Dam and about 11 millimeters (0.43 inches) downstream. Officials said it was possible that the rainfall had been enhanced by the cloud-seeding effort, although they could not conclusively attribute the precipitation to the operation.

The Tokyo government monitored the results before deciding whether to conduct additional cloud-seeding activities. At the time, water storage levels in dams along the Tone River system had fallen to 47 percent of capacity, while dams in the Tama River system stood at 69 percent. Water-use restrictions had already been imposed on reservoirs in the Tone River basin in response to declining supplies.

Tracking Bugs with Radar May Lead to Forecasts of Thunderclouds

In June 2012, the Yomiuri Shimbun reported: “Using meteorological radar to track insects and spiders carried by wind, a team of researchers has observed the formation of thunderclouds, it has been learned. The findings by the researchers, including some from the Meteorological Agency's Meteorological Research Institute (MRI), may lead to technology that will allow meteorologists to predict the generation of cumulonimbus clouds, the researchers said. [Source: Yomiuri Shimbun, June 4, 2012]

Cumulonimbus clouds produce thunderstorms, and sometimes tornadoes.Thunderclouds are spawned when an ascending current is generated at a place where cool air meets warmer air carried in winds blowing from different directions. Using a meteorological radar system installed at Haneda Airport, the research group observed insects and other tiny creatures floating about 500 meters above the ground in western Tokyo on the afternoon of Aug. 7, 2011.

“The bugs, which the researchers said probably included Mymaridae bees and spiders, were believed to be buoyed by winds at a place where cool wind from Tokyo Bay converged with warm wind on land. The study group subsequently confirmed the formation of thunderclouds directly above the site while tracking the bugs, mostly about one millimeter across, as they were carried into the sky on columns of air, the team said.

See China, Nature, Weather

Image Sources: 1) 2) 3) JNTO 4) British Museum 5) Ray Kinnane 6) Hector Garcia site 7) NASA, Wikimedia Commons,

Text Sources: Japan National Tourist Organization (JNTO), CIA World Factbook], Library of Congress, Daily Yomiuri, National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Encyclopedia.com, Live Science, The Conversation, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Google AI, Wikipedia, The Guardian and various websites, books and other publications.

Last updated June 2026