Sea surface temperature in Japanese waters is quite high, and there are concerns about the impact on heavy winter snow [Ocean summary 2025/10/5-11]

2025/10/15 14:40

Typhoons No. 22 and No. 23 have passed through the sea south of Japan one after another since the beginning of October, stirring the seawater in the Pacific Ocean and expanding areas where the sea surface temperature is near normal.

On the other hand, few low-pressure systems have passed through the Japanese waters since the beginning of this month, making it difficult for the
seawater to be stirred.

Sea surface temperatures in the Japanese waters continue to be higher than normal,
up to 4c higher.

If the sea surface temperature in the Japanese Sea continues to be quite high,
in winter, when strong cold air flows in, the warmth of the Sea of Japan and the coldness of the cold air will become more intense, making it easier for snow clouds (as well as rain clouds and thunderclouds) to develop.

This winter, starting in December, temperatures are expected to be lower than normal,
making us more susceptible to cold air.

We need to pay closer attention to the high sea surface temperatures in the Japanese waters and heavy snowfall on the Japan Sea side this winter.

Below is a summary of the ocean from October 5th to 11th, 2025.



#Pressure distribution and waves
On the 5th and 6th, Typhoon No. 22 developed near the Ogasawara Islands and slowly moved west to northwest.
The wave height was 4 to 5 meters near the center of the typhoon.

On the 6th, isobars were crowded between the high pressure system overhanging the continent and the low pressure system east of
Hokkaido.
In the waters of Japan, winds from the north prevailed and wave heights rose to 3 meters.

From the 7th to the 9th, Typhoon No. 22 was very strong and approached the Izu Islands quite a bit.
On the 9th, waves of 12m in height occurred in the Izu Islands, and the Kanto region also experienced severe flooding with a height of 7m.

In the afternoon of the 8th, Typhoon No. 23 formed in the east of the Philippines.
From the 9th to the 10th, Typhoon No. 23 approached the Nansei Islands while intensifying.

On the 11th, we gradually changed our course to the east.
On the 11th, the wave height was 4m near the Nansei Islands.





#Sea surface temperature
Sea surface temperatures in the Japanese waters continued to be significantly higher than normal,
at a maximum of 4c.
In the East China Sea, areas that are significantly higher than normal have expanded.

In the Nansei Islands, the sea area where the sea area is much higher than normal has shrunk, but
the area where the sea area is much higher than normal has continued.
On the Pacific side, areas with higher-than-normal conditions have shrunk, and
areas with higher-than-normal conditions have expanded.

Off the coast of Sanriku, the sea area was much higher than normal.
The sea area off the southeastern coast of Hokkaido continues to be lower than normal.
The Sea of Okhotsk was higher than normal, and
the coast remained fairly high.

[Autumn rain front becomes more active] Warning-level heavy rain will occur in Tohoku and Hokuriku tomorrow, and there will be "storm and snow" in Hokkaido on the weekend -Weekly weather-

2025/10/15 12:43

#Weekly Weather Points#
Tomorrow (Thursday): A low pressure system passes, causing warning-level heavy rain in Tohoku, Hokuriku, etc.
Saturday and Sunday: A rapidly developing low pressure system passes, causing a storm to rage in Hokkaido
First half of next week: Strong cold air intruding into the sky, and the first snow in Hokkaido's flatlands




Today, the 15th (Wednesday), the autumn rain front has moved down to the south coast of Honshu and is stagnant.

A low-pressure system will form on the front tonight,
The low-pressure system is expected to develop slightly until tomorrow, the 16th (Thursday), when it will pass from Hokuriku to Tohoku.

Particularly in the Tohoku and Hokuriku regions, which are close to the center of the low pressure system,
heavy rain is expected to be accompanied by thunder, and there are likely to be warning-level heavy rains in some places.


From noon until late at night on the 16th tomorrow (Thursday),
caution and vigilance is required for landslides, flooding of low-lying areas, and rising river waters.



On Friday the 17th, the low pressure system will move away to the east of Japan, but the next front or low pressure system is expected to approach from the
continent.

From the 18th (Saturday) to the 19th (Sunday), a low pressure front is expected to rapidly develop and pass near Hokkaido,
raising the risk of stronger rain and wind.

Especially in Hokkaido, which is close to the center of the low pressure system,
there is a possibility that a storm warning will be issued widely on the 19th (Sunday), and
it is likely to be very stormy weather.

Airplanes and other aircraft may be affected, so
Please pay attention to traffic information when going out.

After the low pressure system passes on the 19th (Sunday), strong cold air will flow into the upper atmosphere.

Cold air that brings snow in the mountains moves south to northern Tohoku, and
strong cold air that brings snow to the plains flows over northern Hokkaido.

The cold air is expected to remain until at least the 22nd (Wednesday), and
In Hokkaido, snow will fall next week even in flat areas.
There will be some places where the first snow will be observed.



Next week, cold air will flow in from the north,
a front will stay on the southern coast of Honshu, and there will be many cloudy and rainy days,
temperatures will continue to drop into next week.

Next week in particular, the maximum temperature will not reach 20 degrees Celsius in the Kanto region, and
it will feel like autumn is deepening all at once.

The mornings and evenings will also be cold, and the autumn leaves will continue to change in northern Japan and high altitude areas.

Until the weekend, there will be some summer days above 25c, but
the season will move forward next week.
Please be careful not to get sick due to the temperature difference.

Today, the 15th, the sky is cloudy in western and eastern Japan. Tomorrow, the 16th, there is a heavy rain warning mainly on the Sea of ??Japan side.

2025/10/15 07:35

Today, the 15th (Wednesday), high pressure will cover northern Japan near Honshu, and a front will remain stationary from central China to the Pacific side of eastern Japan. It will rain in the Kanto and Tokai regions in the morning, but frontal activity will be weak and the rain will be limited in the afternoon.



It will be sunny in many places in northern Japan. However, in some parts of Hokkaido, there are likely to be temporary showers in the morning due to the effects of a trough in atmospheric pressure. The weather will improve by the afternoon.

In eastern Japan, it will likely rain until morning in the Kanto and Tokai regions. The rain will stop in many places in the afternoon, but the sky will be cloudy and cloudy. It can feel chilly because the sunlight is hard to reach. Adjust your body temperature with clothing.
In the Izu Islands, there is a possibility of very heavy rain accompanied by thunder before noon on Hachijo Island due to the influence of developed rain clouds moving south. Please be careful of heavy rain.

Western Japan has a cloudy sky with a chance of showers in places. Rain clouds tend to remain in the Kii Peninsula and Shikoku, and the weather is likely to be rainy on and off. There may be some localized lightning, so please be careful of lightning strikes.



The front near western Japan will gradually move northward into tonight, and a new low pressure system is expected to form in the East China Sea above the front. The low pressure system above the front will move eastward over the Sea of Japan until tomorrow, the 16th, and the front will become more active, making it easier for rain clouds to develop.



Tomorrow, the 16th, the rain will spread over the Sea of Japan side of western and eastern Japan from the morning, and the rain will peak around noon. In the Tohoku, Hokuriku, and Sanin regions, heavy rain accompanied by thunder is expected in some places, and there is a possibility of heavy rain reaching warning level. Please be careful of landslides and flooding of roads, and be careful of lightning strikes, tornadoes, and other gusts of wind.

2025 First Fall Foliage Forecast: The best time to see autumn leaves is expected to be later than normal nationwide

2025/10/15 06:45

Today, the 15th (Wednesday), our company Sunny Spot announced the first forecast for the best time to see autumn leaves in 2025. Please use this as a reference when planning your next fall foliage viewing trip.

This summer has seen record high temperatures, combined with light rain in some places. This is thought to have an effect on the coloration of the leaves.

It is expected that the trend of high average temperatures across the country will continue. However, the weather tends to change periodically, and on sunny days in the morning and evening, radiation cooling is expected to lower the temperature necessary for leaves to change color.
The best time to see autumn leaves nationwide will be around normal or later than normal.



+Northern Japan (Hokkaido/Tohoku)
In Hokkaido, temperatures are expected to be lower than normal from mid-October to late October. For this reason, in many areas of Hokkaido, the colors will progress from mid-October to late October, and many places will be at their best. In the Tohoku region, temperatures will be lower than normal in late October due to the influence of cold air, but temperatures are likely to be higher than normal until early November. In many places, the best time to see the autumn leaves will be at or later than normal.

+Eastern Japan (Kanto-Koshin, Hokuriku, Tokai)
The average temperature is expected to remain higher than normal until early November. As a result, the best time to see the cherry blossoms is likely to be later than normal in many areas. Around November, it gets colder in the mornings and evenings, so the number of places along the mountains where the best time to see the cherry blossoms will be in late November will gradually increase. The best time to see them in the plains is probably in early December. The best time to see them in central Tokyo is expected to be around December 4th.

+Western Japan (Kinki, Chugoku, Shikoku, Kyushu)
Western Japan will be slow to change color due to the lingering heat that continues into October. Around November, the mornings become colder and the best time to see them is in many places, especially along the mountains. In the plains, it is expected that the weather will be similar to or later than normal in many places. In many places, the best time to see them is from late November to early December, and in Fukuoka, the best time to see them is around December 4th.

General Winter suddenly arrives. Northern Japan experiences "very low temperatures." Next week will be a "first snow rush" in the flatlands of Hokkaido [Early weather information]

2025/10/15 01:39

Today, October 14th (Tuesday), the Japan Meteorological Agency announced early weather information that temperatures from October 20th to 28th will be ``considerably low'' in Hokkaido and Tohoku,
while ``considerably high'' in Okinawa and Amami.



Looking at the weather map for the coming week, a low-pressure system is expected to rapidly develop and pass near Hokkaido from October 18th (Saturday) to October 19th (Sunday),
with the possibility of heavy storms and warning-level heavy rain mainly in northern Japan.

After this low pressure system passes, the area around Japan is expected to have a "high pressure pattern in the west and low pressure in the east."

There is strong cold air behind the low pressure system,
in the early part of next week, strong cold air is expected to flow into the skies over Hokkaido
, bringing snow on the flatlands.



On the 18th (Saturday), warm air will flow towards a low pressure system.
Any precipitation will likely turn into rain in many places.

However, on the 19th (Sunday), cold air is expected to flow into the northern Tohoku region, bringing snow on the
mountains with temperatures around 1,500 meters above 0c.

Furthermore, on Monday the 20th, cold air with temperatures below -6c will hit northern Hokkaido, bringing snow in the plains.

Since the beginning of this month,
cold air strong enough to cause snow to fall in the mountains of Hokkaido has flowed in several times,
but this is the first time that cold air strong enough to cause snow to fall even on the flatlands has flown in.
This season's first ``Winter General has arrived'' can be said.


The day before yesterday, October 12th (Sunday),
the highest temperature was recorded at 35.0c in Kimotsuki Maeda, Kimotsuki Town, Kagoshima Prefecture,
making it the latest "scorchingly hot day" in Japan, but
next week, winter air will suddenly arrive from the north.

It can be said that this year's "autumn" was quite short.

On the other hand, temperatures will continue to be high in Okinawa and Amami, and
in late October it is likely that some places will experience the highest temperatures in 10 years.

We continue to need to be careful about the heat in Okinawa and Amami.




Temperatures will continue to decline nationwide into next week.

In inland areas such as Asahikawa in Hokkaido, the forecast is for rain or snow from the 19th (Sunday).

The season will quickly progress into next week.
Please be careful not to get sick due to changes in temperature.

[New typhoon egg] Typhoon season continues Typhoon No. 23 will become an extratropical cyclone by tonight

2025/10/14 12:52

As of 9 a.m. today, October 14, strong Typhoon No. 23 is moving eastward in the east of Japan at a speed of 45 kilometers per hour.

Typhoon No. 23 is expected to become an extratropical cyclone far east of Japan by tonight.



Meanwhile, a new typhoon egg "tropical cyclone" is expected to form over the southern ocean.

Looking at the forecast weather map for the night of tomorrow, October 15th (Wednesday),
there is a tropical cyclone over the sea east of the Philippines.



A low pressure system consisting of warm air with a maximum wind speed of less than 17.2m/s near the
center is called a "tropical cyclone", and a low pressure system with
maximum wind speed of 17.2m/s or more is called a "typhoon".


It is not yet known whether the tropical cyclone that will form by tomorrow night will turn into a typhoon, but it is possible that it will continue to move west and affect Okinawa and the Sakishima Islands after the weekend.

Please continue to check the latest weather information.

Currently, Typhoon No. 23, which is located in the east of Japan, also approached Japan after forming in the Mariana Islands.
Please be aware that typhoons that form in the east of the Philippines and near the Mariana Islands in October often approach Japan.

October is still typhoon season.
Pay close attention to the trends of typhoons and tropical cyclones.

[New typhoon egg] Typhoon season continues Typhoon No. 23 will become an extratropical cyclone by tonight

2025/10/14 12:42

As of 9 a.m. today, October 14, strong Typhoon No. 23 is moving eastward in the east of Japan at a speed of 45 kilometers per hour.

Typhoon No. 23 is expected to become an extratropical cyclone far east of Japan by tonight.



Meanwhile, a new typhoon egg "tropical cyclone" is expected to form over the southern ocean.

Looking at the forecast weather map for the night of tomorrow, October 15th (Wednesday),
there is a tropical cyclone over the sea east of the Philippines.



When the maximum wind speed near the
center of a cyclone composed of warm air is less than 17.2m/s, it is called a "tropical cyclone", and when the
maximum wind speed is 17.2m/s or more, it is called a "typhoon".

This year's Typhoon No. 23 also occurred in the Mariana Islands and approached Japan.
Typhoons that form in the east of the Philippines and near the Mariana Islands in October often approach Japan, so you need to be careful.

October is still typhoon season.

It is not yet known whether the tropical cyclone that will form by tomorrow night will turn into a
typhoon, but it is possible that it will move westward and affect Okinawa and the Sakishima Islands after the
weekend.

Please continue to check the latest weather information.

[New typhoon egg] Typhoon season continues Typhoon No. 23 will become an extratropical cyclone by tonight

2025/10/14 12:42

As of 9 a.m. today, October 14, strong Typhoon No. 23 is moving eastward in the east of Japan at a speed of 45 kilometers per hour.

Typhoon No. 23 is expected to become an extratropical cyclone far east of Japan by tonight.



Meanwhile, a new typhoon egg "tropical cyclone" is expected to form over the southern ocean.

Looking at the forecast weather map for the night of tomorrow, October 15th (Wednesday),
there is a tropical cyclone over the sea east of the Philippines.



When the maximum wind speed near the
center of a cyclone composed of warm air is less than 17.2m/s, it is called a "tropical cyclone", and when the
maximum wind speed is 17.2m/s or more, it is called a "typhoon".

This year's Typhoon No. 23 also occurred in the Mariana Islands and approached Japan.
Typhoons that form in the east of the Philippines and near the Mariana Islands in October often approach Japan, so you need to be careful.

October is still typhoon season.

It is not yet known whether the tropical cyclone that will form by tomorrow night will turn into a
typhoon, but it is possible that it will move westward and affect Okinawa and the Sakishima Islands after the
weekend.

Please continue to check the latest weather information.

Strong typhoon No. 23 moves away from the Izu Islands, but watch out for high waves tonight

2025/10/13 19:00

As of 18:00 today, the 13th, strong typhoon No. 23 is moving eastward at a speed of 35 km/h in the southeastern Kanto region, moving away from the Izu Islands.

#Typhoon No. 23 13th (Monday) 18:00
==================/br Center position Southeast of Kanto
Strength Strong
Movement East 35km/h
Central pressure 975 hPa
Maximum wind speed 35 m/s (near the center)
Maximum instantaneous wind speed 50 m/s
==================



Typhoon No. 23 will continue to move eastward, and is expected to move east of Japan and away from the Izu Islands by early morning on the 14th tomorrow. In the Izu Islands, the impact of Typhoon No. 23 has diminished, but heavy swells and swells continue. Hachijo Town and Aogashima Village should be on alert for high waves with swells into late tonight.

#Expected wave height (with swells)
+Expected wave height for today, the 13th
Northern Izu Islands 4m
Southern Izu Islands 6m
+Forecasted wave height on tomorrow 14th
Southern Izu Islands 5m


In addition, the ground is loose in some places due to the heavy rains so far. Even after the rain has stopped, there is a risk of landslides, so please continue to exercise caution late tonight.

Meteorological satellite Himawari 9 disrupted as typhoon approaches

2025/10/13 11:52

The Japan Meteorological Agency announced that a disturbance occurred in the observation of the geostationary meteorological satellite "Himawari 9" from around 0:30 yesterday, October 12th.
For a time, it was impossible to observe all satellite images.

Although the exact cause is unknown, the observation equipment needs to be cooled down to a specified temperature in order to provide normal observation data, and as this cooling process requires additional time, it is expected that it will take some time before data provision starts.

This failure caused multiple content updates, including the Japan Meteorological Agency's website ``Meteorological Satellite Himawari,'' and the inability to distribute data outside the Japan Meteorological Agency.

On the same day, the Japan Meteorological Agency gradually switched over to observation by the standby Himawari-8, and from 22:00, provision to the Japan Meteorological Agency, other organizations, and private organizations resumed.

The Japan Meteorological Agency will continue to investigate the problem of "Himawari 9" and will continue to provide information via "Himawari 8" for the time being.