What is the cradle of typhoons, "Monsoon Gyre" Approaching the true nature of the huge vortex that creates typhoons one after another

2026/09/09 15:26

From August 13th to the early hours of August 14th, a linear precipitation band occurred in Chiba Prefecture, and Chiba City experienced record-breaking heavy rain with 24-hour precipitation reaching 351.0 mm.
About three weeks later, on September 5th, heavy rain was observed on Yakushima due to Typhoon No. 24, with 490.5 mm of rainfall in 24 hours.

The phenomenon known as ``monsoon gyre,'' which is secretly attracting attention in the meteorological industry with a great deal of alarm, is behind the continuous attack of linear precipitation belts caused by tropical cyclones and other forces.
It's not a word you're used to hearing, but this is an atmospheric vortex that could be called a "giant typhoon manufacturing factory."
We will explain in an easy-to-understand way what this thing is and how it affects our lives.

1. What is the true identity of "Monsoon Gyre"

A monsoon gyre is a super-massive cyclonic gyre with a diameter of 1,000 kilometers that appears from summer to autumn in the northwestern Pacific Ocean from Southeast Asia. The scale of these typhoons is an order of magnitude different from that of ordinary small cyclones and typhoons, and they can be several times the size of the Japanese archipelago. Its most distinctive feature is that it is not just a mass of rain clouds, but rather acts as a cradle for producing typhoons one after another. Moist air is violently stirred up in this gigantic vortex, making it easy for abnormal situations such as one typhoon to disappear, but another typhoon or tropical cyclone to form one after another right next to or behind it.



2. Why is the monsoon gyre a threat

When the monsoon gyre occurs, it has a troubling impact on our lives and weather.
Just when one typhoon approaches and makes landfall in Japan and we feel relieved that it has finally passed, there are many cases where a second or third typhoon arrives following a similar course.
This will hinder recovery efforts in the affected areas and increase the risk of long-term heavy rain disasters. In addition, when the Autumn rain front that is stationary near Japan and the warm, humid air around the edge of the monsoon gyre merge, the frontal activity increases explosively. Even if the typhoon itself does not directly hit, linear precipitation bands can form in faraway places, causing heavy rain.
It may be still fresh in your memory that a tropical cyclone south of Shikoku created a linear precipitation belt in the Tokai region, and heavy rain of 104.5 mm per hour was recorded in Nagoya, Aichi Prefecture.
Another aspect is the prolonged period of unseasonable weather. Because the entire sky is completely covered by a huge vortex, cloudy and rainy days tend to last for days or even weeks. There are also concerns about the lack of sunlight and its associated impact on the prices of agricultural products such as vegetables.

3.How should we respond to the monsoon gyre

The term monsoon gyre itself may not appear directly in weather forecasts, but when the news explains that ``moist air from the south will continue to flow in for a long period of time,'' it is a sign that this huge vortex is lurking in the background. The best way to protect yourself in the upcoming season is to not let your guard down based on just one typhoon information, but to be aware of long-term preparations that look several days ahead, such as whether there are reserves for subsequent typhoons or whether there is a risk of disaster due to a long period of rain.

[Breaking News] Level 4 flood danger warning has been announced for the Hida River in the Kiso River system. The basin is on high alert for river flooding and landslides.

2026/09/09 11:40

Due to heavy rain, the Hida River in the Kiso River system in Gifu Prefecture has risen, and a Level 4 flood warning has been issued.



The flood level reached the Gero standard observation station on the Hida River, and if flooding occurs, there is a risk of flooding in areas such as Gero City, a basin municipality.

Please ensure your own safety by never going near rivers and moving to an upper floor that is less likely to be flooded.



Today, the 9th (Wednesday), record heavy rain has been occurring in the Tokai region since yesterday due to the influence of the autumn rain front and low pressure. Active rain clouds are still hanging over the basin intermittently, and the amount of rain in the area is increasing today. The area around
is not only at high risk of flooding due to heavy rain, but also the risk of landslides occurring is extremely high.

If you live in areas where there is a risk of landslides, such as near cliffs or rivers, please try to evacuate early and pay attention to information such as evacuation advisories announced by municipalities.

9th (Wednesday): Possibility of linear precipitation bands in Tokai, Kinki, and Shikoku; very heavy rain over a wide area.

2026/09/09 07:55

Please be extremely cautious of landslides, especially from western Japan to eastern Japan, and be wary of inundation of low-lying land, rising water levels, and flooding of rivers. In the Tokai, Kinki, and Shikoku regions, there is a risk that linear precipitation bands will form and the risk of heavy rain disasters will rapidly increase. In addition, there is a risk of heavy rain in the Kanto-Koshin region at night.

A front is extending from western Japan to eastern Japan, passing through the Pacific side of eastern Japan. Furthermore, a tropical cyclone that has changed from Typhoon No. 24 is heading north in the south of Shikoku, and as warm, humid air flows into the front from the east, the front becomes more active, causing heavy rain to fall in some places. The tropical cyclone is expected to turn into a frontal cyclone on the Pacific side of western Japan, and frontal activity is expected to remain active into the 10th (Thursday).



As a result, very heavy rain and thunderstorms are expected to fall over a wide area from western Japan to the Tohoku region, resulting in heavy rainfall. In particular, heavy rain will continue from the Pacific side of western Japan to eastern Japan into the 10th, potentially increasing the total amount of rainfall. The Japan Meteorological Agency has announced a half-day-a-day forecast for 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.



Please be extremely cautious of flooding of low-lying land, rising water levels and flooding of rivers. Caution and vigilance are also required for landslides, flooding of low-lying land, and rising river waters.

Please pay close attention to changes in weather conditions, such as frequently checking the latest information.

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.