[High sea surface temperatures continue] Sea of Japan and the seas around Hokkaido: up to 5-6 C higher than normal Ocean Summary 2025/8/3 - 8/9

2025/08/14 15:55

The sea surface temperatures continued to be higher than normal in the Japanese Sea and the waters surrounding Hokkaido, and were up to 5-6 C higher than normal.
Below is a summary of the oceans [August 3, 2025 - August 9]



#Pressure arrangement and waves
On the 3rd, Typhoon No. 9 moved eastward in Japan.
Also, at 9am, Typhoon No. 10 broke out east of Hachijojima, moving northeasterly east of Japan.
On the 4th, Typhoon No. 9 was transformed into a temperate cyclone far east of Japan at 3pm.
Typhoon No. 10 moved eastward in Japan.
The waves rose in the east of Japan, causing it to slam in the area around the typhoon.
From the 5th to the 6th, Typhoon No. 10 proceeded far east in Japan, turning into a temperate cyclone at 9am on the 6th.
Also, on the 8th, fronts passed around Honshu one after another, causing waves to rise slightly in the waters near Japan.
Typhoon No. 11 broke out in the Mariana Islands at 9am on the 8th.
Typhoon No. 11 headed north to the waters near Ogasawara on the 9th, causing a major storm around Typhoon No. 11.



#Sea surface temperature
The sea surface temperature in the Japanese Sea has been significantly higher than normal due to low pressure and passing fronts, and gradually it has become slightly higher than normal in the west and central parts.
In the East China Sea, the sea area remains at an average level.
On the Pacific side, the waters remained at normal levels, and in the east of Japan, where Typhoon No. 10 passed, the waters slightly lower than normal increased.
The off Sanriku area continued to be slightly higher than normal.
In the waters around Hokkaido, waters that were much higher than normal continued. In the Sea of Okhotsk, the temperature was up to 6 C higher than normal.

Obon - End of Obon - The dangerous heat that exceeds the temperature is revived - Warning of sudden changes in weather - Low pressure in the vicinity of northern Japan and front lines passing one after another

2025/08/14 12:06

Weekly weather forecast for Obon to end of Bon
#Dangerous heat that exceeds body temperature is revived; the Pacific high pressure system is becoming stronger
#Warning for sudden changes in weather, not only in the mountains, but also in the plains
#Low pressure and fronts pass through the northern part of Northern Japan one after another



#Dangerous heat that exceeds body temperature is coming back to power
Today, the 14th (Thursday), the Pacific high pressure system was strengthening, and the front that caused heavy rain on Japan the other day is moving north to the Korean Peninsula.
For the past few days, the heat around Japan has been calming due to the rain caused by the front line.
However, due to the growing influence of the Pacific High Pressure over the next week, it is expected to clear up, especially in western and eastern Japan.
And then the dangerous heat that exceeds the body temperature has returned.
Again, there are more places where the highest temperature is over 35 C, and there will be some places where the temperature is dangerously high, not only in western Japan but also in eastern Japan, where the temperature is dangerously high, especially inland areas.
In areas where a heatstroke warning alert has been issued, try to spend your time in a cooler environment with air conditioning indoors, taking frequent breaks, hydrate and salt.
This is a summer vacation, and it is a time when three generations of people go out more, but elderly people, infants, and young children are prone to heat stroke, so be careful and people around you should also talk to them.
Even in areas where heatstroke warning alerts have not been announced, when leisure activities outdoors, be sure to take thorough measures against heatstroke, such as drinking plenty of hydration, using hats and parasols, and taking breaks in cool places.



#Beware of sudden weather changes Not only in mountain leisure activities, but sunny days are expected in western and eastern Japan, but air condition is likely to become unstable due to rising daytime temperatures and the effects of humid air.
Please be careful of sudden changes in the weather.
In the afternoon, rain clouds will likely develop, mainly inland areas and along mountains.
When leisure activities on the mountain, be careful of changes in the sky and make safety your number one priority.
Also, rain clouds can flow into the plains, so it's safe to have an umbrella that can be used in both sunny and rainy areas.



#Low pressure and fronts are expected to pass through the area around northern Japan
Low pressure and fronts are expected to pass through the area around northern Japan.
In northern Japan, there will be more rainy days, mainly on the Sea of Japan side. Care must be taken as there is a risk of heavy rain or thunderstorms locally.
On the days when the sun is exposed, the temperature will exceed 30 C.

The heat is back. The next week is so hot

2025/08/13 17:16

A stagnant front extends from the East Sea of Japan through the South of Kanto, the Tokai region, and the Sea of Japan in the Yellow Sea.
In addition, there are cyclones on the east and Yellow Sea fronts of Japan, moving northeast.
On the other hand, there is a high pressure system in the northern Sea of Japan and the southern Sea of Japan, moving east and west respectively.

Today, the front line activities that caused heavy rain during the three-day holiday gradually weakened, and many areas were sunny, mainly in northern Japan and Kyushu.
The heat has returned to western Japan and the temperature has risen, and as of 4pm, there were 603 midsummer days across the country with a temperature of 30c and 24 extremely hot days of 35c or higher.




For the next week from tomorrow onwards, there will be many days when the high pressure will be covered in sunny and warm air, so
There are more and more places with hottest temperatures with a maximum of 35 degrees or higher up until mid-next week, the 20th (Wednesday), and the temperatures are expected to continue to be high in various places.




As a heat stroke prevention measure, it is important to stay hydrated frequently and avoid the heat.
It is important to avoid direct sunlight, especially when going out, by wearing a parasol or hat, and using the shade.
Also, don't worry about being indoors, and try to keep up with proper hydration and temperature control.



Specific measures to prevent heatstroke are as follows.

1. Avoid the heat:
When going out: Wear a parasol or hat and use the shade. Avoid going out during hot times.
Indoor: Make sure to control the temperature appropriately (use air conditioners and fans appropriately). Make sure to ventilate frequently.
When active: Don't overdo it on hot days and take frequent breaks.

2. Hydration:
Relax: Refreshing hydration frequently during the hot season to prevent dehydration.
Drinks suitable for hydration: Barley tea, oral rehydration solutions, sports drinks, etc. are suitable.

3. Salt supplement:
Salt supplement when sweating: It is also important to replenish the salt that is lost along with sweat.
Foods suitable for replenishing salt: Add a little salt to umeboshi, salted kelp, rice balls and other foods.

4. Clothing:
Breathable Clothing: Wear clothes made of breathable materials (cotton, linen, etc.).
Moisture-absorbing and quick-drying underwear: Choose underwear that is excellent in moisture-absorbing and quick-drying.

5. Health management:
Notes when you are not feeling well:
Special care is required when you are not feeling well, as the risk of heatstroke increases.
Note for the elderly:
Special care is required in elderly people as their temperature control function decreases.



In addition to health management such as heat stroke prevention, please be careful about managing agricultural products, livestock, etc.

Isesaki City, Gunma Prefecture, the highest highest temperature in history in Japan; special heavy rain warning in Kirishima City, Kagoshima Prefecture (August 3 - August 9, 2025)

2025/08/13 07:33

Here is a summary of the weather during this period (August 3rd to August 9th).

#Summary of weather for this period (August 3rd to August 9th)
The average temperature was covered by a tall, warm high pressure system, and in many places, especially in northern and eastern Japan, it exceeded normal. The temperature exceeded the average temperature in the Sea of Okhotsk side and the Pacific side of Hokkaido, and in Kanto, the temperature exceeded 3 C, and in Muroran, Maebashi and Tokyo, the temperature exceeded 3 C and in Kushiro.

Pressure exceeded normal years in northern Japan, Hokuriku, and Kyushu, which had heavy rain due to low pressure and fronts. In Kushiro, Akita, and Niigata, the number was about 4 to 5 times the average year, and in Kanazawa, where linear precipitation occurred, the number was about 12 times the average year. In Nagasaki, the total rainfall was about four times higher than normal, and in Kagoshima, the total rainfall was about twice higher than normal.

Sunday hours have increased cloudy and rainy days due to the effects of low pressure and fronts, and many areas have fallen below normal in the Sea of Japan side of Northern Japan, Hokuriku, and Western Japan. In the northern and eastern Japan Pacific side, there were many sunny days throughout the period, so many areas had more sunlight than usual.



[About the weather during this period]
#Characteristics of the atmospheric pressure arrangement
On the 3rd, high pressure was covered in the area around Honshu, and typhoon No. 10 occurred near the Izu Islands. The tropical cyclone of former Typhoon No. 8 traveled northeasterly through the East China Sea. On the 4th, Typhoon No. 10 left Japan's Tokai region. A low pressure system, derived from the warm, humid air of former Typhoon No. 8, is moving eastward from the Korean Peninsula. On the 5th, a low pressure system accompanied by a front passed through Hokkaido from the Sea of Japan. The front line stagnates near the Sea of Japan. Around Honshu, a pressure arrangement was formed at the southern and northern and low levels. On the 6th, the front line traveled east to west from Tohoku to Hanachu, and a low pressure system on the front line traveled eastward from the Korean Peninsula into the Sea of Japan. On the 7th, the low pressure system developed and progressed to the area near Hokkaido, and the front line from the center of the low pressure system stagnated from Tohoku to Hanachu. On the 8th, the front gradually moved south towards the southern coast of Honshu, and stagnated from the Chinese coast to the Kanto coastline, over Japan's Tokai. Typhoon No. 11 broke out near the Mariana Islands. On the 9th, the front line ran from Huachu through Kyushu and stagnated over Japan's Tokai region. In the south of Japan, Typhoon No. 11 moved westward.

#Precture
On the 3rd, the atmosphere became unstable due to rising temperatures during the day, and localized rain and thunderstorms along mountains and inland in the west and eastern Japan. Heavy rain of 44.0mm/h was observed in Shinshu Shinmachi, Nagano City. On the 4th, the rain began mainly in western Japan due to the effects of warm, humid air heading towards the low pressure system. Very heavy rain at 59.0mm/h was observed in Akune City, Kagoshima Prefecture. On the 5th, due to low pressure and the effects of fronts, there was record-breaking rain, mainly on the Sea of Okhotsk side of Hokkaido and the Sea of Japan side of Tohoku. The rains were extremely heavy, breaking the number one record in Kushiro City, Hokkaido (65.0mm/h) and Noshiro City, Akita Prefecture (65.0mm/h). On the 6th, heavy rain began to occur mainly in the Hokuriku region due to the influence of the front line. In Hashimo, Sado City, Niigata Prefecture, the highest recorded daily precipitation of 280mm. On the 7th, a linear precipitation zone occurred near the Kaga region of Ishikawa Prefecture at dawn. In Kanazawa, record heavy rainfall of 332.0mm is 24-hour rainfall. On the 8th, a special warning about heavy rain was issued in the early hours of the morning, with linear precipitation occurring near Kirishima City, Kagoshima Prefecture. On the 9th, heavy rain began mainly in northern Kyushu, near the front line, and a linear precipitation zone occurred around Fukuoka Prefecture late at night.

#Temperature
On the 3rd, warm air around 1500m above spread from western Japan to Tohoku, and it was extremely hot in various places. The number of hot spots is 319. On the 4th, strong sunlight and the warm air above caused a wide range of heat. In Komatsu City, Ishikawa Prefecture, the temperature reached 40.3 degrees Celsius, causing a dangerous heat. On the 5th, in the Kanto region, in addition to the warm air of about 1,500m above, the Fohn phenomenon caused by airflow across the mountain overlapped, causing high temperatures. In Isesaki City, Gunma Prefecture, the highest temperature in the nation was observed at 41.8 C. On the 6th, many hot spots continued to appear near Honshu, with Shizuoka City reaching 41.4 C, the second highest in history in the country. Central Tokyo (37.0c) marks the fifth consecutive day of extreme heat, while Yokohama (38.1c) marks the highest temperature ever recorded. On the 7th, due to the influence of the front, there were many cloudy and rainy areas, and the number of hot and hot spots decreased to 12 spots, 233 less than the previous day. On the 8th, temperatures rose, mainly in the inland areas of Tokai and Kanto. 36.9c is in Kiryu City, Gunma Prefecture. It's a hot day at 35.0 C in central Tokyo. On the 9th, the heat eased slightly due to the rain, and only two hot spots were in Nagoya (35.5c) and Tottori (35.2c).

El Nino Surveillance News: It is likely to be in peacetime in winter.

2025/08/12 20:00

The Japan Meteorological Agency announced the latest El Nino surveillance news on Tuesday, the 12th.


The sea surface temperature in the monitored sea area continues to be normal, and neither the El Nino nor La Nina phenomenon has occurred, so the situation continues to be normal.
In the future, there is a possibility that the state will temporarily become closer to the La Nina phenomenon around autumn, but this condition is predicted to not last long.


The difference from the standard sea surface temperature in the El Nino monitoring waters in July was -0.1 C, which was close to the standard. In addition, the five-month moving average used to determine the occurrence of El Nino and La Nina phenomena was +0.1 C in May, which was close to the standard value.
Sea surface temperatures in the Pacific equator region were higher than normal in the western part and lower than normal in the central part, while the eastern part was closer to normal.
The eastern winds (trade winds) in the lower atmosphere of the Pacific equator were stronger than normal in the central region, and were around average in the eastern region.
Convection activity became more active near Indonesia, but around the date line in the Pacific equatorial region, it was about the same as normal.
From the above process, the situation has become a peacetime state, not occurring either the El Nino or La Nina phenomenon.



According to forecasts from the Japan Meteorological Agency's Atmospheric Ocean Coupling Model, trade winds will continue to remain strong in the Pacific equator into the fall, and sea surface temperatures in the surveillance waters will fall. However, this condition does not last long, and we expect the sea surface temperature to rise over winter, approaching the standard value. Also, live commentary shows that cold water has not accumulated throughout the Pacific equator. Based on the above, it is possible that the condition may be close to the La Nina phenomenon around autumn, but this condition does not last long and is likely to continue in peacetime through winter (60%).


#What is the El Nino/La Nina phenomenon
The El Nino phenomenon is a phenomenon in which the sea surface temperature increases above normal from the Pacific equatorial region to the South American coast, and this condition continues for about a year.


On the other hand, the phenomenon in which the sea surface temperature continues to be lower than normal in the same sea area is called the La Nina phenomenon.


Once the El Nino or La Nina phenomenon occurs, it is thought that abnormal weather will occur around the world, including in Japan.

Typhoon No. 11 (Paudre) Tonight - tomorrow (Wed) With a storm zone, strong forces approach the Sakishima Islands in Okinawa [Typhoon Information]

2025/08/12 11:25

Typhoon No. 11 (Podl) is expected to approach Okinawa's Sakishima Islands with strong forces from tonight, accompanied by a
storm zone.



Typhoon No. 11 (Podl) is located at 9am today, the 12th, south of Okinawa and is moving west at 25km/h.

The central pressure is 980hPa, and the maximum wind speed near the center is 30m/s
The maximum instantaneous wind speed is 45m/s.

Typhoon No. 11 will develop further in the future, and is expected to become a "strong" force by the morning.


We will approach Okinawa's Sakishima Islands from tonight until the morning of the 13th (Wednesday) with a storm zone.

In the Sakishima Islands, tomorrow, the 13th (Wednesday), we will be careful of high waves accompanied by swells and be careful of strong winds.
Please note that depending on the course of the typhoon, there is a risk of a storm tomorrow.



[Wave prediction]
Today, Tuesday the 12th, Okinawa main island region 4 meters with swell
Miyakojima region 5 meters with swell
Yaeyama region 5 meters with swell
Tomorrow, Wednesday the 13th, Okinawa main island region 4 meters with swell
Miyakojima region 5 meters with swell
Yaeyama region 6 meters with swell

[Wind forecast: Maximum wind speed (maximum instantaneous wind speed)]
Today, Tuesday the 12th, Miyakojima region 17 meters (30 meters)
Yaeyama region 18 meters (30 meters)
Wednesday, the 13th
Miyakojima region 17 meters (30 meters)
Yaeyama region 20 meters (30 meters)
















/--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


Before the winds get stronger, take measures against typhoons early, such as removing items that are easily blown around the house.

Also, the atmosphere becomes unstable, so please be careful of severe gusts of wind such as lightning strikes and tornadoes.

Warning against heavy rain disasters, mainly on the Sea of Japan side; in Nagasaki prefecture, linear precipitation zones may occur

2025/08/12 06:35

The front runs from the East China Sea through the Sea of Japan side of western Japan and eastern Japan, and into the Tohoku region, with a low pressure system in the western Sea of Japan on the front line moving eastward.
With warm, humid air flowing into the front and low pressure lines, the atmosphere is extremely unstable, with some areas having heavy rainfall with lightning.


In Ashibe, Iki City, Nagasaki Prefecture, extremely heavy rain of 51.5mm is observed in the hour until 4:30am.
As of 6:20am, heavy rain warnings have been issued mainly in areas on the Sea of Japan side from Hokuriku to Kyushu, and some areas have issued landslide warning information in Niigata, Ishikawa, Yamaguchi, and Fukuoka prefectures.

From tomorrow, the 13th, the front will stagnate from the Sea of Japan side of western Japan and eastern Japan in the Tohoku region, and the low pressure system on the front is expected to advance to the Hokuriku region by the evening of the 12th. For this reason, extremely unstable atmospheres will continue from western to northern Japan.




[Rain Prediction]
From western Japan to northern Japan, heavy rain or very heavy rain will fall with thunder, causing heavy rain.
#Expected rainfall (at high places)
+Expected 24-hour precipitation by the dawn of the day tomorrow, the 13th
Tohoku region: 80mm
Kanto-Koshin region: 80mm
Hokuriku region: 100mm
Tokai region: 100mm
Chugoku region: 80mm
Northern Kyushu region: 80mm
If a linear precipitation occurs, the rainfall may increase locally even further.
The following areas and periods where linear precipitation zones can cause a sudden increase in the risk of heavy rain disasters.
Nature Kyushu Region, Nagasaki Prefecture
Today, the morning of the 12th

[Disaster Prevention Issues]
From western Japan to northern Japan, be vigilant and be careful of landslides, and be careful of low-lying land flooding, river flooding and flooding. Also be careful of severe gusts of wind, such as lightning strikes and tornadoes. If there are signs of developing cumulonimbus clouds approaching, try to ensure your safety by moving inside the building. There is a risk of falling hail, so be careful when managing agricultural crops and agricultural facilities.

Weather today, Tuesday the 12th: Warning of heavy rain, mainly on the Sea of Japan side; Kyushu is over its peak, but remain vigilant

2025/08/12 06:04

Today, the 12th (Tuesday), after the holidays, the front will stagnate on the Sea of Japan side of eastern Japan and western Japan, and a low pressure system is expected to progress along the front. Warnings against heavy rain are necessary, mainly on the front line and the Sea of Japan side, which is close to low pressure. Even on the Pacific side, the rain is getting stronger, so the sky is not careless.



Although there are some sunny days in Hokkaido, the sky is dominated by clouds. There is a possibility of showers, so it's safe to have rain gear when you go out.


Due to the effects of the front, the weather in West Japan and East Japan continues to be prone to rain. The rainy mountain passes are expected to gradually exceed the record-breaking rainfall in northern Kyushu yesterday, but the ground has been loosened due to record-breaking heavy rain so far. In northern Kyushu, rain is intermittently falling today, so even if it rains a little, we need to be vigilant for landslides and river flooding.


There is also a risk of heavy rain on the Sea of Japan side from Sanin to Hokuriku and Tohoku, which are close to the front. Extreme vigilance is required for landslides, flooding in lowlands, flooding and flooding of rivers.
There are areas where rain is getting stronger on the Pacific side, such as Tokai, so please bring rain gear when you go out.
The sky pattern is also changing in Kanto. Even if it's not raining when you're out, it would be a good idea to have rain gear.


Due to the influence of Typhoon No. 11, the winds will gradually increase, mainly in the Sakishima Islands, and waves will increase at sea. Try to stay away from the coast as close as possible.


There are probably many places where you can feel hot and humid in all areas. It would be a good idea to choose clothes that are breathable.

Typhoon No. 11 approaches Okinawa and the Sakishima Islands with strong forces from Tuesday the 12th to Wednesday the 13th

2025/08/11 16:41

Typhoon No. 11, at 9am on the 11th, is 21 10 minutes north latitude and 133 25 minutes east longitude, travels west at 9am on the 11th.
In the future, it is expected to continue moving from the south of Japan to the west of Okinawa, and to approach the Sakishima Islands with strong forces from the 12th to the 13th.


The Sakishima Islands are expected to have a major storm starting from the 12th, and a storm is expected on the 13th.
Beware of high waves with storms and swells.
You need to take early typhoon measures before the wind intensifies.




#Wave forecast
Wave height expected on the 12th
Okinawa main island region 4 meters with swells
Miyakojima region 5 meters with swells
Yaeyama region 6 meters with swells

Wave height expected on the 13th
Okinawa main island region 4 meters with swells
Miyakojima region 6 meters with swells
Yaeyama region 7 meters with swells

#Wind forecast

Wind direction and maximum wind speed expected on the 12th (maximum instantaneous wind speed)
Miyakojima region: Northeastern winds: 18 meters (30 meters)
Yaeyama region: Northeastern winds: 18 meters (30 meters)

Wind direction and maximum wind speed expected on the 13th (maximum instantaneous wind speed)
Miyakojima region: Eastern winds: 23 meters (35 meters)


#Rain forecast
There is a high 24-hour precipitation expected from 12:00 on the 12th to 12:00 on the 13th,






















































































































































































Beware of strong winds.
Also, the wind is expected to be stronger on the 13th and become a storm.
In the Yaeyama region, beware of storms.
Please note that in the Miyakojima region, the 13th, there is a risk of a storm occurring depending on the course of the typhoon.
In the Sakishima Islands, early typhoon measures are necessary before the winds get stronger.
Coastal waters will be swelled in the Okinawa main island region and the Sakishima Islands from the 12th, and are expected to gradually become more severe in the Sakishima Islands.
Please be careful and be careful of high waves with swells.
In the Yaeyama region, depending on the course of the typhoon, there is a risk of heavy rain at the warning level on the 13th.
Please be careful of landslides, flooding of low land, and flooding of rivers.
In the Sakishima Islands, be careful of severe gusts of winds such as lightning and tornadoes under cumulonimbus clouds that have developed since the 12th, and sudden heavy rain.
If there are signs of developing cumulonimbus clouds approaching, try to ensure safety by moving inside the building.

Kumamoto Prefecture has announced special heavy rain warning to make it the most vigilance for heavy rain disasters

2025/08/11 01:02

The front extends from the East China Sea through the Sea of Japan side of western Japan and extends into the Tohoku region, with a low pressure system on the
front moving northeasterly through the western Sea of Japan. Warm and humid air flows into this front, causing the atmosphere to be extremely unstable and there are places where extremely heavy rain with lightning.



In northern Kyushu, linear precipitation zones have occurred, with fierce rainfall intermittently, marking record heavy rain exceeding 400 mm in 24 hours of precipitation until 9pm on the 10th. A special heavy rain warning has been issued in Kumamoto Prefecture.
It is highly likely that some kind of disaster has already occurred in Kumamoto Prefecture, and
Life is approaching. Make sure you are safe immediately.
In other areas, the risk of landslides, floods, and flood damage is also extremely high. Please be very careful.


Also, the front will stagnate from the Sea of Japan side of western Japan to the Tohoku region through the 12th, and low pressure systems are expected to pass through the front one after another.
For this reason, extremely unstable atmospheres will continue from western Japan to northern Japan.
Please be careful of landslides, flooding of low land, flooding of rivers and flooding from the 12th over a wide area of western Japan to northern Japan.



###Rain forecast
In Northern Japan to Western Japan, very heavy or intense rain will fall with thunder, causing heavy rain.
There is a high 24-hour precipitation expected from midnight on the 11th to midnight on the 12th, and
Tohoku region: 80mm
Kanto-Koshin region: 200mm
Hokuriku region: 100mm
Tokai region: 250mm
Kinki region: 180mm
Chugoku region: 100mm
Shikoku region: 250mm
Northern Kyushu region: 250mm
Southern Kyushu region: 200mm
brAfter that, the 24-hour precipitation expected from midnight on the 12th to midnight on the 13th is high, and if a linear precipitation occurs, there is a risk that the rainfall will increase locally even more.
The areas and periods where linear precipitation zones can suddenly increase due to the risk of heavy rain disasters are as follows:

#To the morning of the 11th
/Fukuoka Prefecture, Saga Prefecture, Nagasaki Prefecture, Kumamoto Prefecture, Oita Prefecture

#To the afternoon of the 11th