Atmospheric instability continues in various places tomorrow, the 13th (Thursday); be careful of heavy rain accompanied by intermittent thunderstorms

2026/08/12 18:38

Tomorrow, the 13th (Thursday), rain will be more likely to fall from western Japan to the Kanto region and the Pacific side of the Tohoku region due to the influence of moist air blowing in from the tropical cyclone that replaced Typhoon No. 15 and the high pressure system near Chishima. Please be careful as there are places where it will rain heavily with thunder.





The Kanto and Tohoku Pacific sides continue to experience rainy weather due to the influence of warm, humid air blowing toward the tropical cyclone and humid air blowing in from the high pressure near the Chishima Islands. The atmospheric conditions are likely to be extremely unstable due to the influence of cold air in the upper atmosphere. There is a risk of heavy or extremely heavy rain in localized areas, so please be on guard against flooding of roads, flooding of low-lying land, and landslides.
Please be sure to prepare rain gear such as a folding umbrella when going out.

Also, in western Japan, the atmospheric conditions will be unstable due to the influence of moist air blowing in from tropical cyclones, and the weather will be changeable. Rain is expected to start to fall suddenly in some places, and it may be heavy for a while.




The predicted 24-hour precipitation from 18:00 on the 12th to 18:00 on the 13th is expected to be 120 mm in the Tohoku region.
Kanto-Koshin region 100mm
Tokai region 180mm
Kinki region 150mm

Expected.


On the other hand, with the timing of sunlight reaching mainly western Japan, the temperature is likely to rise. It will be a midsummer day with temperatures exceeding 30 degrees Celsius in many places.
As the heat and humidity increases, please take precautions against heat stroke if you are going to be outdoors for a long time.

Weather and temperature summary (August 2nd to August 8th) Typhoon No. 13 hits the main island of Okinawa. Record-breaking heat continues in western Japan

2026/08/12 14:53

This is a summary of the weather and temperature from August 2nd to August 8th, 2026.

[About this period's weather]

#Characteristics of pressure distribution
On the 2nd, the Sea of Okhotsk anticyclone moved eastward, and the Pacific anticyclone centered near the East China Sea almost stagnated. Additionally, a front extends from the Tohoku region to the east of Japan, and a low pressure system moves eastward above the front. In addition, Typhoon No. 13 was moving west-northwest near Minamitorishima with extremely strong force. On the 3rd, the high pressure system centered over the East China Sea was almost stagnant. Typhoon No. 13 remained large and extremely powerful as it moved westward through the waters near Ogasawara. On the 4th, a large and extremely strong typhoon No. 13 continued to move westward near Ogasawara. On the 5th, the area around Japan was gently covered by high pressure systems centered far east of Japan and near the Yellow Sea, and a large and extremely strong typhoon moved westward south of Japan. On the 6th, a large and strong typhoon No. 13 moved westward northeast of Minami Daito Island, engulfing the Daito Island region in a stormy area. On the 7th, a large and extremely strong typhoon No. 13 continued to advance westward near the main island of Okinawa. The Daito Island region, Okinawa main island, and Amami were all within the typhoon's storm range. On the 8th, a large and extremely strong typhoon passed near the main island of Okinawa. It moved westward through the East China Sea.

#Precipitation
On the 2nd, rain continued in Tohoku due to a front. On the other hand, the atmospheric conditions in the Kanto and Tokai regions were extremely unstable, with extremely heavy rain falling at 61.5 mm/h in Ena, Gifu Prefecture, and 60.0 mm/h in Kanuma City, Tochigi Prefecture. Atmospheric conditions remained unstable in the Kinki and Kanto regions on the 3rd. A heavy rain warning has been announced in Osaka Prefecture. On the 4th, there was unstable precipitation in Kyushu and the Chugoku region. Due to the approach of Typhoon No. 13, it rained on the Ogasawara Islands, and 102.0 mm/day was observed on Hahajima. On the 5th, it rained mainly in the Daitojima region due to Typhoon No. 13. There were also places on the Pacific side of eastern Japan and western Japan with rain. On the 6th, due to Typhoon No. 13, it rained in places from the Sea of Japan side of western Japan to Okinawa. Locally, the rain became stronger, with heavy rain falling in southern Kyushu. On the 7th, heavy rain was observed in Okinawa and Amami due to rain clouds from the typhoon itself. Heavy rain occurred in Naze, Amami City, Kagoshima Prefecture, with daily maximum rainfall exceeding 300 mm, including 335.5 mm. On the 8th, Typhoon No. 13 brought strong winds and rain to a wide area of the Nansei Islands. In northern and eastern Japan, there were places in Ishikawa Town, Fukushima Prefecture, where there was heavy rainfall of 92.0 mm/h due to the influence of humid air.

#Temperature
The heat was particularly severe on the 2nd in western Japan, which was covered with hot air in the upper atmosphere, with extremely hot days of 40.8 degrees Celsius observed at multiple locations in Ekawasaki, Shimanto City, Kochi Prefecture. It was record-breaking heat, breaking the record for August at 59 locations nationwide, and breaking the record for record-setting heat at 45 locations. On the 3rd, temperatures were extremely high in western Japan, with temperatures exceeding body temperature in many places, including Kumamoto City at 40.3 degrees Celsius and Saga City at 40.2 degrees Celsius. On the other hand, temperatures in the Kanto region, where easterly winds blow from the sea, were slow to rise. On the 4th, it was extremely hot mainly in western Japan due to the effects of high pressure. In the Pacific side of northern and eastern Japan, the rise in temperature was suppressed by the northeast airflow of the Sea of Okhotsk High. On the 5th, temperatures rose in the Sea of Japan and western Kyushu due to airflow over the mountains. On the 6th, sunlight reached western Japan and eastern Japan on the Sea of Japan side. In addition, due to the southerly winds of the typhoon, a feng occurred on the Sea of Japan side. Temperature rises are particularly noticeable from southern Kyushu to the Chugoku region. 39.0c in Yatsushiro City, Kumamoto Prefecture, 38.9c in Tottori, etc. From the 7th to the 8th, temperatures continued to be strong mainly on the Sea of Japan side, with temperatures of 39.6 C observed in Ota City, Shimane Prefecture on the 7th, and 38.9 C in Fukuchiyama City, Kyoto Prefecture on the 8th.




#Summary of the weather for this period (August 2nd to August 8th)
The average temperature was extremely hot in western Japan, which was covered by an anticyclone, and reached record high temperatures mainly in the Chugoku region, northern Kyushu, and the East China Sea side, and extremely hot days were recorded in Kyushu. On the other hand, in the Tohoku Pacific side and the Kanto region, where cool easterly winds from the Sea of Okhotsk high pressure system blew, temperatures were at or below normal in many locations.
Precipitation was higher than normal in Hokuriku, which was susceptible to the effects of the seasonal rain front, Kinki, where atmospheric conditions were prone to instability, and the Nansei Islands, which was affected by Typhoon No. 13, with some places experiencing heavy rain. On the other hand, other regions were covered in high pressure for many days throughout the period, so the total precipitation for the period was lower than normal or significantly lower, with many locations reaching 0 mm.
Sunshine hours tended to exceed normal years, with many sunny days covered by high pressure throughout the country. On the other hand, in the Nansei Islands and southern Kyushu, which were susceptible to the effects of Typhoon No. 13 and humid air, temperatures tended to be below normal with many cloudy and rainy days.

Typhoon No. 15 turns into a tropical cyclone; watch out for sudden, short-term heavy rain from Tohoku to the Chugoku region from the afternoon onwards

2026/08/12 12:43

Typhoon No. 15 turned into a tropical cyclone in the Sea of Japan around 9 a.m. today, Wednesday, the 12th.

However, the warm, humid air brought in by Typhoon No. 15 remains in the vicinity of Japan, and the combination of the effects of cold air in the upper atmosphere has made the atmospheric conditions unstable. Dense rain clouds can be seen in places from Tohoku to the Chugoku region, with intermittent rain falling, and in some places the rain is becoming heavier.



Looking at the probability of lightning striking at 6:00 pm today, the 12th (Wednesday), the probability of lightning striking is expected to be high in areas such as the Tohoku Pacific side, Kanto, and Kinki. Even though there may be a break in the rain, rain clouds and thunderclouds will continue to form easily, and there is a risk that heavy rain of 30mm or more per hour may fall in localized areas.

Today, the 12th (Wednesday), please be careful of sudden changes in the weather from the afternoon. Sufficient attention should be paid to landslides, flooding of low-lying areas, flooding of roads, and sudden rises and flooding of rivers. Also, please be careful of thunderstorms, tornadoes, and other strong gusts of wind.



In coastal areas, waves will continue to be high with swells, so please be careful of high waves. It is also the spring tide season, and storm surge is expected to occur in some places. Currently, there are places in Kagawa Prefecture where a Level 3 storm surge warning has been issued, including Takamatsu City. Please be wary of rising tide levels due to storm surge.

[Typhoon information] New typhoon No. 17 (Nanka) occurs near Ogasawara

2026/08/12 11:26

At around 9 a.m. today, the 12th (Wednesday), a tropical cyclone that was developing near the Ogasawara Islands became Typhoon No. 17.
Typhoon No. 17 is moving east-northeast at a slow speed, with a central pressure of 994 hPa, maximum wind speed near the center of 18 m/s, and maximum instantaneous wind speed of 25 m/s.

#Typhoon No.17 12th (Wed) As of 9:00 am
===================
Size Ogasawara vicinity
Traveling speed East-northeast Slowly
Central pressure 994hPa
Maximum wind speed 18m/s (near the center)
Maximum instantaneous wind speed 25m/s
===================

Typhoon No. 17 is expected to continue heading northeast while increasing its speed, reaching the sea east of Ogasawara around 9am tomorrow. There is a possibility that the Ogasawara Islands will enter the strong wind region of a typhoon in the future, so please be careful of strong winds and high waves accompanied by swells.

Typhoon No. 17 is expected to continue moving northward over the eastern seaboard of Japan. There is a wide range of forecasts at this point, so there is some uncertainty, but there is a possibility that it will affect the area around Japan again from next week onwards. Please pay attention to the typhoon information that will be updated in the future.

[Typhoon information] Typhoon No. 15 moves west toward the Sea of Japan. Beware of heavy rain, strong winds, and high waves

2026/08/12 08:06

As of 6 a.m. today, the 12th (Wednesday), Typhoon No. 15 is located approximately 40 km east-northeast of Tsuruga City and is moving westward at a speed of approximately 35 km per hour.
After this, Typhoon No. 15 is expected to move further west and become a tropical cyclone off the coast of San'in by early afternoon today.

#Typhoon No. 15 12th (Wednesday) 6:00 a.m.
==================
Center location: Approximately 40km east-northeast of Tsuruga City
Direction of movement, speed: West 35km/ h
Central pressure 996hPa
Maximum wind speed 18m/s (near the center)
Maximum instantaneous wind speed 25m/s
==================



Typhoon No. 15 made landfall in southern Ibaraki Prefecture at around 8 pm yesterday, Tuesday, the 11th. The typhoon then passed through the Kanto-Koshin region, and as of 6 a.m. today, Wednesday, the 12th, the typhoon's center was moving west near Tsuruga City, Fukui Prefecture.

Rain fell across a wide area of northern and western Japan, and in Miura, Miura City, Kanagawa Prefecture, heavy rain of 40.5 mm was observed in the hour up to 3:20 a.m.

Typhoon No. 15 is expected to continue moving westward and become a tropical cyclone off the coast of San'in by early afternoon today, but people from Tohoku to western Japan should continue to be careful of strong winds, high waves, and heavy rain. In particular, rain is expected to continue in the Tohoku and Kanto regions even after the typhoon has left the region, as moist air flows in from easterly winds.

Strong winds will blow from eastern Japan to western Japan today, the 12th (Wednesday), causing heavy swells.
In addition, the atmospheric conditions will be unstable due to the effects of warm, humid air flowing into the typhoon and cold air in the upper atmosphere, so heavy or very heavy rain with thunder is expected to occur in a wide area from the Tohoku region to western Japan today, the 12th (Wednesday), resulting in heavy rain in some places.

In addition, as the effects of spring tides and typhoons overlap, the tide level will rise in eastern Japan today, the 12th (Wednesday), and in western Japan, tomorrow the 13th (Thursday), resulting in high tides and storm surges in some places.





[Rain Forecast]
Tohoku region 150 mm
Tohoku region 150mm
Kanto-Koshin region 120 mm
Tokai region 150 mm
Kinki region 150 mm
[Disaster prevention matters]
Today, the 12th (Wednesday), please be extremely cautious of landslides in the Tohoku region. In addition, in the Tohoku region and the Kanto-Koshin region, please be wary of flooding of low-lying land, rising water levels and flooding of rivers.
In western Japan, please be on high alert for high tides until tomorrow the 13th (Thursday).
From the Tohoku region to western Japan today, the 12th (Wednesday), please be careful of strong gusts of wind that could cause lightning and tornadoes. If there are signs that a cumulonimbus cloud is approaching, please take precautions such as moving inside a building. There is also a risk of hail, so please be careful when managing crops and agricultural facilities.

[Typhoon Information] Typhoon No. 15 makes landfall in southern Ibaraki Prefecture

2026/08/11 20:53

Typhoon No. 15 made landfall in the southern part of Ibaraki Prefecture around 8 pm today, Tuesday, the 11th.



Typhoon No. 15 is currently moving westward at a speed of 20km per hour, and is expected to pass through the Kanto-Koshin region and near Gifu City tomorrow morning.



Currently, it is raining over a wide area from Tohoku to eastern Japan.
In the future, there is a risk that strong rain clouds will form over a wide area of eastern Japan, including the Kanto-Koshin region, which is close to the path of the typhoon, and on the Pacific coast of Tohoku, where warm, humid air flows in from the sea.There is a risk that heavy or very heavy rain accompanied by thunder may result in heavy rain.
Tomorrow, the 12th (Wednesday), it will start raining in the morning on the Sea of Japan side of western Japan, and in the afternoon it will rain over a wide area of western Japan.

In addition, strong winds are widespread across Tohoku and eastern Japan, and as of 8:30 p.m. today, a storm warning has been issued for Fukushima, Ibaraki, and Chiba prefectures. Waves are high at sea, and a wave warning has been issued for coastal areas from Aomori to Chiba prefectures.

Please pay attention to upcoming weather information.

New typhoon forecast: Possibility of approaching the Japanese archipelago from the east of Japan again

2026/08/11 17:45

At 3:00 p.m. today, the 11th, the Japan Meteorological Agency announced that the tropical cyclone currently developing in southern Japan is "expected to develop into a typhoon within the next 24 hours." The next time it occurs, it will be called Typhoon No. 17, making it the third typhoon this month.

#Tropical cyclone 11th (Tuesday) 15:00
==================
Center location South of Japan
Moving East Slowly
Central pressure 998 hPa
Maximum wind speed 15 m/s (near the center)
Maximum instantaneous wind speed 25 m/s
==================



The tropical cyclone is expected to move eastward and develop into a typhoon tomorrow, Wednesday the 12th. It is then expected to change its course northward near Ogasawara around the 13th (Thursday), move northwest until around the 16th (Sunday), and head east toward Japan.
Although the forecast circle is still large and the course has not been determined, it is expected to follow a similar course to Typhoon No. 15, and may approach the Japanese archipelago from the east of Japan, so it is necessary to pay close attention to future typhoon information.

Typhoon No. 15 will make landfall in the Kanto region around the beginning of the night. Beware of heavy rain and strong winds.

2026/08/11 12:28

As of 12:00 noon today, Tuesday, the 11th, strong Typhoon No. 15 is located approximately 180 km east-southeast of Iwaki City and is moving westward at a speed of approximately 30 km per hour.

#Typhoon No.15 11th (Tue) 11:00
==================/br Center position Location: Approximately 180km
east-southeast of Iwaki City Travel: West 30km/h
Central pressure: 985 hPa
Maximum wind speed 23 m/s (near the center)
Maximum instantaneous wind speed 35 m/s
==================



The region from Tohoku to Kanto has entered the region of strong winds, and the winds are starting to strengthen mainly in the coastal areas. The maximum instantaneous wind speed was 21.0 m/s in Sendai City, Miyagi Prefecture, 20.6 m/s in Hachinohe City, Aomori Prefecture, and 19.3 m/s in Onahama, Iwaki City, Fukushima Prefecture. As of 11:30 a.m., storm warnings and wave warnings have been issued for a wide range of areas on the Pacific coast from Iwate Prefecture to Chiba Prefecture.

Typhoon No. 15 will continue to move westward, and there is a high possibility that it will make landfall in Ibaraki Prefecture around the beginning of the night on the 11th.
It will be the first time since statistics began in 1951 that it will land in Ibaraki Prefecture.
After making landfall, it is expected to move westwards until the 12th (Tuesday), and after reaching western Japan, it is expected to turn into a tropical cyclone by the morning of the 13th (Thursday) the next day.

In Tohoku and eastern Japan, rain and wind are expected to gradually increase from around evening today as the typhoon approaches. Winds can momentarily exceed 30 m/s, so please take precautions against typhoons, such as moving outdoor items that are easily blown away indoors, charging mobile batteries, and preparing flashlights in case of a power outage.

Also, rain is falling in the Tohoku region, far away from the typhoon, and is increasing in intensity. In the Tohoku region, heavy rain of over 30mm per hour is expected to occur, leading to heavy rain in some places. Please be extremely cautious of landslides caused by heavy rain.
Atmospheric conditions are expected to be extremely unstable from eastern Japan to western Japan until tomorrow, the 12th (Wednesday), due to the influence of warm, humid air flowing into the typhoon and cold air in the upper atmosphere. Heavy rain will fall over a wide area, and extremely heavy rain of 50 mm or more per hour will occur in some places, so vigilance is needed to avoid flooding of low-lying land and rising and flooding rivers.



#Expected amount of rain (in areas where there is a lot)
+Precipitation expected for 24 hours by 12:00 tomorrow 12th (Wednesday)
Tohoku region 180mm
Kanto Koshin region 180mm
Hokuriku region 80mm
Tokai region 120mm
+24-hour precipitation expected by 12:00 on Thursday the 13th
Tohoku region 120mm
Kanto-Koshin region 80mm
Hokuriku region 80mm
Tokai region 150mm
Kinki region 120mm

#Expected wind strength
+Maximum wind speed (maximum instantaneous wind speed) expected today, 11th
Tohoku region 25m/s (35m/s)
Kanto-Koshin region 25m/s (35m/s)
Hokuriku region 18m/s (30m/s)
Tokai region 17m/s (30m/s)
+Tomorrow 12 Maximum wind speed (maximum instantaneous wind speed) expected on Sunday (Wednesday)
Tohoku region 15m/s (25m/s)
Kanto-Koshin region 17m/s (30m/s)
Hokuriku Region: 18m/s (30m/s)
Tokai region: 15m/s (25m/s)

Expected wave height
Tohoku region 7m
Kanto region 7m
+Expected wave height for tomorrow 12th (Wednesday)
Tohoku region 5m
Kanto region 5m

Typhoon No. 15 approaches Kanto region; warning of heavy rain and strong winds over wide area

2026/08/11 07:02

Typhoon No. 15 was located east of Iwaki City, Fukushima Prefecture at 6am on the 11th, and was moving west-northwest at a speed of approximately 35km/hr.

The typhoon is developing and moving westward, approaching the Kanto region on the afternoon of the 11th, and there is a risk of it making landfall.



In eastern Japan, which is close to the path of the typhoon, warm and humid air is expected to flow in.
Currently, there is cold air above the Kanto region, and due to this, the atmospheric conditions will be extremely unstable.

On the 11th, heavy to very heavy rain is expected to fall over a wide area from the Tohoku region to eastern Japan, with some localized areas expected to experience heavy rain.
Please be extremely cautious of landslides through the 12th.



Very strong winds will blow in the Tohoku region and eastern Japan, and there will be places on the Pacific side where there will be swells and severe winds.

Typhoon No. 15 is expected to move westward through eastern Japan and turn into a tropical cyclone on the Sea of Japan side of western Japan on the 12th.

[Rain Forecast]
Expected 24-hour precipitation from 6:00 on the 11th to 6:00 on the 12th will be heavy in the Tohoku region. 180mm
Kanto-Koshin region 150mm
Izu Islands 100mm

Then on the 12th from 6:00 to 13 The predicted 24-hour precipitation by 6 o'clock on Sunday is high in some places:
Tohoku region 120mm
Kanto-Koshin region 120mm
br Tokai region 150 mm

[Wind forecast]
Maximum wind speed expected on the 11th (maximum instantaneous wind speed)
Tohoku region Direction: 25 meters (35 meters)
Kanto-Koshin region 25 meters (35 meters)
Hokuriku region 18 meters (30 meters)
Tokai region 17 meters (30 meters)

Maximum wind speed expected on the 12th (max. Instantaneous wind speed)
Tohoku region 15 meters (25 meters)
Kanto-Koshin region 17 meters (30 meters)
Hokuriku region 18 meters (30 meters)
Tokai region 15 meters (25 meters)



[Wave forecast]
Expected wave height on the 11th
Tohoku region 7 meters with swells
Kanto region 7 meters With swells

Wave height expected on the 12th
Tohoku region 5 meters with swells
Kanto region 5 meters with swells

Typhoon No. 15 likely to land tomorrow; heavy rain and strong winds in eastern Japan

2026/08/10 19:24

Typhoon No. 15 was in the east of Japan at 6pm on the 10th and was moving north-northwest at a speed of approximately 20 km per hour.



The typhoon will gradually change course to the west as it continues to develop, and will approach the Kanto-Koshin region on the afternoon of the 11th, with the risk of making landfall. In eastern Japan, which is close to the typhoon's path, warm, humid air will flow in, and the atmospheric conditions will be extremely unstable due to the influence of cold air in the upper atmosphere.

On the 11th, heavy to very heavy rain is expected to fall over a wide area from the Tohoku region to eastern Japan, with some localized areas expected to experience heavy rain. In the Tohoku region, please be on high alert for landslides on the 11th. In the Tohoku and Kanto-Koshin regions, be wary of inundation of low-lying land, rising water levels and flooding of rivers.



Atmospheric conditions will be unstable in eastern Japan on the 11th, so please be careful of strong gusts such as lightning and tornadoes. If there are signs that a cumulonimbus cloud is approaching, please take precautions such as moving inside a building. There is also a risk of hail, so please be careful when managing crops and agricultural facilities.

On the Pacific side, there will be strong winds and swells, leading to severe conditions in some places. Please be on guard for strong winds and high waves accompanied by swells on the 11th in the Pacific side of the Tohoku region and the Kanto region.



[Rain Forecast]
24-hour precipitation expected from 18:00 on the 10th to 18:00 on the 11th (where there is a lot)
Tohoku region 150mm

24-hour precipitation expected from 18:00 on the 11th to 18:00 on the 12th (where there is a lot)
Tohoku region 120mm
Kanto-Koshin region 150 mm
Tokai region 100 mm
[Wind forecast]
Maximum wind speed expected on the 11th ( Maximum instantaneous wind speed)
Tohoku region 25 meters (35 meters)
Kanto region 25 meters (35 meters)
Hokuriku region Maximum wind speed (maximum instantaneous wind speed) expected on the 12th
Kanto region 15 meters (30 meters)
Hokuriku region 18 meters (30 meters)

[Wave forecast]
Wave height expected on the 11th
Tohoku region 8 meters with swells
Kanto region 7 meters with swells
Wave height expected on the 12th
Kanto region 5 meters with swells

The typhoon is expected to move westward through eastern Japan and turn into a tropical cyclone on the Sea of Japan side of western Japan on the 12th.
Even after turning into a tropical cyclone, there is a risk of severe weather near the cyclone.
Please pay attention to the latest information.