Large wave height of over 6m around Typhoon No. 24 [Marine Summary (August 30th to September 5th, 2026)]

2026/09/09 06:57

Throughout the period, the autumn rain front remained stationary near Honshu. Typhoon No. 24 took a counterclockwise circular path near Okinawa and affected the Nansei Islands for a long period of time.

Below is a summary of the ocean (August 30th to September 5th, 2026)



#Pressure distribution and waves
Autumn rain front is stationary near Honshu. From the 30th to the 31st, a low pressure system moved southeast off the coast of Sanriku, with wave heights of around 3 meters in the vicinity. A tropical cyclone off the coast of Sanriku moves northward south of Japan. Wave height is 3m near the low pressure area. On the 1st, the tropical cyclone developed into Typhoon No. 24. Wave height was around 3m near the center of the typhoon and the Nansei Islands on the north side of the typhoon. For the next 2-3 days, the typhoon slowed down and stalled near the Nansei Islands. Waves in the vicinity of the Nansei Islands had a wave height of more than 6 meters. On the 4th, Typhoon No. 24 moved slowly northward, with wave heights of over 4 meters from the south of Kyushu to the Tsushima Strait. On the 5th, Typhoon No. 24 moved into the East China Sea, with wave heights of over 6 meters near the center and over 2 meters on the southern coast of Honshu.



#Sea surface temperature
In the Japanese sea area, areas where the sea surface temperature is higher than normal are shrinking. In the East China Sea and the Nansei Islands, areas slightly lower than normal have shrunk. Continuing from the previous week, waters off the coast of Shikoku and the Tokai region continued to be slightly higher than normal. To the east of Kanto, the sea level was slightly higher than normal, and off the coast of Sanriku, areas appeared to be at normal levels. Sea areas significantly higher than normal were no longer observed off the southeastern coast of Hokkaido, near the Kuril Islands, and in the Sea of Okhotsk, but sea areas that were higher than normal continued. In the waters around the Kuril Islands, the areas above normal have shrunk, and areas below normal can now be seen.

Level 4 flood risk information in Tokyo - Situation requiring evacuation on rivers in Tokyo

2026/09/08 22:30

There are currently very active rain clouds over the western part of Tokyo and the eastern part of the Tama region. Level 4 flood risk information has been announced for the Shakujii River, Zenpukuji River, Nogawa River, and Sengawa River that flow through Tokyo.



The front is extending from western Japan through the Pacific side of eastern Japan to the east of Japan. Additionally, a tropical cyclone that has changed from Typhoon No. 24 is heading north from the south of Shikoku. To the east, warm, humid air is flowing toward the front, and the front is active, causing heavy rain in some places.



Level 4 is the "evacuate everyone from dangerous areas" stage. If you are in an area that is expected to be inundated by river flooding, please evacuate immediately.

The front is expected to remain active from Tohoku to Western Japan until the 10th.
Please pay attention to information from your local government and the latest risk distribution from the Japan Meteorological Agency's Kikikuru.

Level 5 special flood warning for Shonai River system - Immediate action to protect lives

2026/09/08 19:41

A special level 5 flood warning has been announced for the Shonai River system and Yadagawa River in Aichi Prefecture. There is a risk that rivers are flooding and life is in danger. Please immediately ensure your safety and take extreme caution against rising river water and flooding.

The front is stationary near the southern coast of Honshu, and a tropical cyclone that has changed from Typhoon No. 24 is moving northward south of Shikoku. Warm, humid air is flowing towards the front from the east side of the tropical cyclone, increasing front activity, resulting in locally extremely heavy rain accompanied by thunder.

A special level 5 flood warning has been issued for Aichi Prefecture, and the situation is extremely dangerous, with an extremely high risk of a serious disaster that could endanger lives.





In Chikusa Ward, Nagoya City, Aichi Prefecture, as of 18:00 on the 8th, the 24-hour precipitation was 215.0mm, and the total precipitation since the start of the rain (on the morning of the 3rd) was 278.5mm (preliminary figures).

Active rain clouds will continue to form, and linear precipitation bands will form into the evening of tomorrow, the 9th, potentially increasing the risk of heavy rain disasters.



Please exercise extreme caution against rising water levels and flooding of rivers. In the Tokai region, please be extremely careful about flooding of low-lying land, rising and overflowing rivers, and landslides.

Please pay attention to the latest disaster prevention weather information that will be announced in the future.

Weather for tomorrow 9th (Wednesday): Be careful of heavy rain on the Pacific side

2026/09/08 18:30

A tropical cyclone that has changed from Typhoon No. 24 is expected to be absorbed into the autumn rain front that is stationary along the southern coast of western and eastern Japan.
Rain is likely to fall over a wide area from western Japan to Tohoku, and there is a risk of heavy rain or heavy rain, especially on the Pacific side. In areas with heavy rainfall, even a small amount of rain can cause landslides, so caution is required.



From Kanto to the west, rain will fall over a wide area due to the influence of the autumn rain front and tropical cyclone. There is a risk of heavy rain, especially in Shikoku, Kinki, and the Pacific side of the Tokai region. Rain is expected to become heavier in the Kanto region starting in the evening. Despite the rain, the temperature is expected to rise to around 30c during the day.
Okinawa to southern Kyushu will have some hours of sunshine, and even in northern Kyushu the rain will likely ease in the afternoon.
The weather in Hokkaido and northern Tohoku will start to improve, and the weather will gradually become more sunny in the afternoon. Even though the sun is shining, it will still feel cool. There is a chance of showers in northern Hokkaido.

Linear rain belt may occur in the Tokai region. Heavy rain warning from today 8th to the morning of tomorrow 9th.

2026/09/08 11:57

Today, the 8th (Tuesday), the Japan Meteorological Agency announced general weather commentary information (forecast for linear precipitation bands half a day in advance) for the Tokai region, stating that the risk of heavy rain disasters may rapidly increase due to the formation of linear precipitation bands.

The following are the regions and periods where linear precipitation bands may occur and the risk of heavy rain disasters may rapidly increase.

(Tokai region) Shizuoka prefecture From the evening of the 8th to the morning of the 9th
(Tokai region) Aichi prefecture From the evening of the 8th to the morning of the 9th
(Tokai region) Gifu prefecture From the evening of the 8th to the morning of the 9th
(Tokai region) Mie prefecture From the afternoon of the 8th to the morning of the 9th



The autumn rain front is extending from the vicinity of Shikoku through the coast of the Kanto region to the east of Japan. Additionally, a tropical cyclone that has changed from Typhoon No. 24 is heading north in the waters near the Amami region. To the east, warm, humid air is flowing toward the front, increasing frontal activity.



Currently, there are active rain clouds and heavy rain falling mainly on the Pacific side of western Japan, such as Shikoku and the Kii Peninsula.

The front is expected to move northward and remain mostly stationary from western Japan to eastern Japan until the 10th (Thursday). The tropical cyclone is expected to form a front on the Pacific side of western Japan tomorrow, the 9th (Wednesday), and the front is expected to remain highly active.

As a result, the atmosphere in the Tokai region will continue to be extremely unstable into the 10th (Thursday), with heavy rain accompanied by thunder and extremely heavy rain expected to occur in some places.

Please be wary of flooding of low-lying land, rising water levels and flooding of rivers. In addition, there are places where the ground has become loose due to previous rains, so even a small amount of rainfall can increase the risk of landslides. Please be careful and be on guard against landslides.



Please further increase your preparedness for heavy rain and pay attention to disaster prevention weather information that will be announced in stages. Also, please check the level of risk in your area using Kikikuru (risk distribution of landslides, inundation, and flood disasters) on the Japan Meteorological Agency website.

Weekly weather: Long rain continues. How long will the autumn rain front remain near Honshu

2026/09/08 07:48

Rainy days will continue over a wide area. The autumn rain front, which causes prolonged rain, is expected to remain near Honshu for the next week.



As extremely warm and humid air from the tropics flows into the vicinity of the front, there is a risk that heavy rain will occur from the Pacific side of western Japan to eastern Japan from around the 8th to the 10th, further increasing the total rainfall amount.
In areas that have already experienced record heavy rainfall, there are places where the ground is loose, increasing the risk of landslides even with a little rain. Please stay away from dangerous cliffs and slopes. Also, please be careful of flooding in low-lying areas and rising water in rivers.

Looking at the predicted pressure distribution after that, there is still some uncertainty as to the location of the predicted autumn rain front, but it is expected to remain near Honshu. As a result, rainy days are likely to continue over a wide area around Honshu.





The north side of the front will have autumn air, and in Hokkaido, which tends to be located north of the front, the morning minimum temperature will likely not reach 20c on many days. Please try not to get sick due to changes in temperature. On the other hand, areas south of the front are not expected to experience extreme heat, but on the Pacific side of western Japan, daytime temperatures are expected to reach over 30c in some places even with rain, and it is likely to become humid and humid. Please be careful of heat stroke.

Autumn rain front stagnates; heavy rain continues from Shikoku to Tohoku, total rainfall expected to increase

2026/09/08 07:01

Today, the 8th (Tuesday), the autumn rain front will continue to remain stationary near the southern coast of Honshu. Additionally, the tropical cyclone formerly known as Typhoon No. 24 is moving northward over the sea east of the Amami region and approaching the front.
Very warm and humid air from a tropical cyclone will flow towards the autumn rain front, causing the area of rain to spread, and it is likely that there will be some places where extremely heavy rain of more than 50mm per hour will be accompanied by local thunderstorms.





The area of rain is expected to gradually spread from around noon today, the 8th. Extremely heavy rain is expected to occur in some places in Shikoku and the Tokai region, and in the Tokai region, a linear rain band will form in the afternoon, and the risk of heavy rain disasters may increase rapidly.
The rain is expected to become stronger in some places on the Sea of Japan side, and there are likely to be localized areas of heavy rain around Hokuriku.





The autumn rain front is expected to remain near the southern coast of Honshu tomorrow, the 9th (Wednesday). After a tropical cyclone becomes a frontal cyclone, it becomes indistinct, but the front is expected to remain highly active.
Heavy rain will continue from western Japan to the Pacific side of eastern Japan, and total rainfall is expected to increase further in some places until around the 10th.
In areas where record-breaking rainfall has already occurred, the ground is loose, so even a small amount of rain can increase the risk of landslides.



From western Japan to the Tohoku region, please be careful of landslides, flooding of low-lying areas, and rising and flooding rivers from around the 10th.

Weather for the week: The autumn rain front will remain stationary and the weather will be rainy. Be careful of landslides caused by prolonged rain.

2026/09/07 19:09

Regarding the weather for the next week, the autumn rain front will remain stationary near Honshu, and it is likely that rain and cloudy weather will continue from Tohoku to western Japan.
Due to the influence of warm, humid air flowing in from the tropical cyclone that replaced Typhoon No. 24, the frontal activity will increase, causing heavy rain locally, mainly on the Pacific side. Please check the latest information.



Tomorrow, the 8th (Tuesday), a tropical cyclone south of Japan, which has changed from Typhoon No. 24, is expected to move northward and approach the south of Shikoku. This tropical cyclone will bring in warm, moist air, leading to increased frontal activity. In eastern and western Japan, heavy or extremely heavy rain is expected to occur in some places, especially in the Shikoku region and other parts of the Pacific Ocean. If the developed rain clouds continue to form, there is a possibility of warning-level heavy rain.
Please be careful about flooding of low-lying land, rising river water, and landslides.



The next day, from Wednesday the 9th to Thursday the 10th, the tropical cyclone that changed from Typhoon No. 24 will turn into an extratropical cyclone and is expected to move eastward along the front.
Warm and humid air will continue to flow towards the front, and the front will continue to be active. Atmospheric conditions will become unstable, and there will be places in eastern and western Japan where there will be heavy or extremely heavy rain accompanied by localized thunderstorms.
There are places where the ground has become loose due to previous rain, and even a small amount of rain can increase the risk of landslides.
Please continue to be vigilant.

Even after the 11th (Friday), due to the front staying near Honshu and the effects of a trough in atmospheric pressure, moist air will flow into Honshu, making it likely that rain will continue.

Hokkaido and Okinawa are expected to have some sunny days during this period.




Temperatures in the Kanto region are expected to reach 30c or higher again around Wednesday the 9th, and 33c in Tokyo.
In the Tokai region and western Japan, temperatures are expected to rise around the 13th (Sunday), and Kagoshima will experience an extremely hot day of 34c.
It may feel hot and humid, so don't overdo it, don't forget to hydrate yourself, take breaks, and use the air conditioner appropriately.

The Izu Islands experienced unprecedented heavy rain A tropical cyclone transformed from Typhoon No. 24 is expected to move eastward along the southern coast of Honshu

2026/09/07 17:28

A low pressure system is located on the Pacific coast of the Tohoku region and is moving north-northeast, and a front from the low pressure system is extending off the coast of Shikoku. Warm, humid air moving north on the east side of the tropical cyclone that changed from Typhoon No. 24 is flowing toward the front, and the front is becoming more active.
As a result, the Izu Islands are experiencing record-breaking heavy rainfall, with some places experiencing rainfall in the 24 hours up to 3:00 p.m. on the 7th, exceeding the amount of rainfall in one month of September in a normal year.

The low pressure system will move from the coast of Sanriku to the waters near Chishima until the 8th. The front extending from the low-pressure area off the coast of Shikoku is expected to move northward and become stationary on the Pacific side of western to eastern Japan until around the 10th. The tropical cyclone that changed from Typhoon No. 24 is expected to move northward from the south of Japan and turn into a frontal cyclone near western Japan on the 9th.



Warm and humid air moving northward on the east side of the tropical cyclone will continue to flow toward the front, making the atmospheric condition extremely unstable and leading to increased frontal activity.
For this reason, heavy rain will continue until around the 10th, and total rainfall may increase mainly from the Pacific side of western to eastern Japan.



In the Izu Islands, a Level 5 landslide special warning has been announced. The heavy rain is unprecedented, and there is a high possibility that some kind of disaster has already occurred, and lives are in danger. Please immediately ensure your safety and take maximum precautions against landslides.



Also, near-term forecasts for linear precipitation belts have been announced for the Izu Islands. In the future, there is a risk that linear precipitation bands will occur and the risk of heavy rain disasters will increase rapidly.
On the Pacific side of eastern Japan, please be on high alert for landslides through the 8th, and be wary of flooding of low-lying land, rising water levels, and flooding of rivers.

Immediate prediction of linear rain belt within the next 3 hours in the Izu Islands

2026/09/07 15:55

According to the Japan Meteorological Agency's announcement at 2:18 p.m., a linear precipitation band will form in the northern part of the Izu Islands in Tokyo within the next three hours, increasing the possibility that very heavy rain will continue to fall in the same area. The risk of a life-threatening disaster may increase rapidly.
Please take extra precautions against heavy rain until early evening.



Typhoon No. 24 turned into a
tropical cyclone near Minami Daito Island at 9:00 on the 7th.
Also, a front extending from the southern coast of Honshu to the east of Japan is slowly moving north. Warm, humid air moving north on the east side of the typhoon is flowing toward the front, increasing frontal activity.
As a result, the Izu Islands are experiencing record-breaking heavy rainfall, with some places experiencing 24-hour precipitation exceeding the average September month's worth of precipitation.

A level 5 special landslide warning has been issued for the northern part of the Izu Islands, and a level 4 landslide warning has been issued for the southern part of the Izu Islands.
It would not be surprising if some kind of disaster had already occurred.



There is a risk of a linear precipitation band in the future, and even if a linear precipitation band does not occur, it is predicted that heavy rain will continue.
Immediately move away from low-lying areas and near rivers,
evacuate from cliffs and slopes, etc.
Immediately ensure your own safety and take actions to protect your life.