Due to the influence of fronts and low pressure, barges occur in the east of Japan [Marine summary (May 17-23, 2026)]

2026/05/27 01:33

On May 23rd, a front extending from the south of Japan to the east of Japan and the low pressure above the front strengthened the winds, causing a storm to blow over the east of Japan.
Sea surface temperatures in the Japanese waters continued to be significantly higher than normal in the central and western regions, and were up to 4 C higher on the continental side.

Below is a summary of the ocean (May 17-23, 2026).



#Pressure distribution and waves
On the 17th and 18th, a front extended south of Japan, and there was a large gradient in pressure between it and the high pressure near Japan, and waves rose south of Okinawa.
On the 19th, a low pressure system moved northward near Okinawa, causing waves to rise.
On the 20th, a low pressure system accompanied by a front moved eastward near the Yellow Sea, causing waves to rise.
On the 21st, a low pressure system in the western Japan Sea moved eastward. A front extended east to west around western and eastern Japan. Waves rose in the Sea of Japan and the southern coast of Honshu.
From the 22nd to the 23rd, the front extended from central China to the Nansei Islands to the east of Japan, and the low pressure above the front moved eastward. There was a large pressure gradient between the front and low pressure system and the high pressure system to the north, causing waves to rise in the Sea of Japan and east to south of Japan. On the 23rd, it broke out in the east of Japan.



#Sea surface temperature
Sea surface temperatures in the central and western regions of Japan continued to be significantly higher than normal in the central and western regions, and were up to 4 C higher on the continental side.
In the East China Sea, areas that were much warmer than normal expanded, and were up to 4 C warmer.
The waters near the Nansei Islands remained at normal levels, while the waters south of Japan continued to be slightly higher than normal.
The waters off the coast of the Tokai region were at normal levels, and the waters east of the Kanto region continued to be significantly higher than normal, with temperatures up to 4 C higher than normal.
The area off the coast of Sanriku, which is much lower than normal, has shrunk.
The sea off the southeastern coast of Hokkaido was lower than normal, and the waters near the Kuril Islands and the Sea of Okhotsk remained near normal.

Weather forecast for today, the 26th (Tuesday): It will gradually rain in Kyushu and Shikoku, and there will be very heavy rain in Amami.

2026/05/26 12:13

A front will extend over the southern coast of Kyushu in the afternoon of today, the 26th (Tuesday). Amami is likely to experience locally heavy rain into the evening. There is also a possibility that linear precipitation bands may occur. Rain will spread across Kyushu from around noon, and there will also be more places in Shikoku to experience rain. From the evening onwards, there is likely to be some showers in parts of inland eastern Japan.



Today, the afternoon of the 26th (Tuesday), a front is extending near Kyushu. Warm, humid air is flowing toward the front, and rain clouds and thunderclouds are developing near Amami.
Amami will experience locally heavy to very heavy rain into the evening. Until the afternoon, there is a risk that a linear precipitation band will form and the risk of heavy rain disasters will increase rapidly.



Rain will gradually spread in Kyushu from around noon. It will rain in Shikoku from the evening onwards, and rain gear will be needed in many parts of the country at night.
It will be sunny in many parts of Honshu, but from the evening onwards there will be some showers in inland areas of eastern Japan. In addition, there is a possibility of light rain in parts of northern Hokkaido at night.


The maximum temperature is expected to be above normal in many places today. Temperatures are expected to be around 28 degrees Celsius widely in the Kanto region and west, with midsummer days expected to reach 30 degrees Celsius or higher in some places, mainly in western Japan. In Tohoku, there are places inland where the temperature approaches 30c, and in Hokkaido, there are places in the northern part and the Sea of Okhotsk where the temperature exceeds 25c. Please take precautions against the heat, such as hydrating frequently.

A typhoon egg lies in the sea far south of Japan. Will a new typhoon occur in the future

2026/05/26 08:09

A cluster of clouds can be seen gathering over the ocean near the Caroline Islands, far south of Japan. This cloud mass is analyzed as an L mark (low pressure area) on the Asia-Pacific region weather map as of 3 a.m. today, but there is a possibility that it will develop into a tropical cyclone by tonight.





Looking at the forecast after that, the forecast map at 9pm on the 27th shows that it is predicted to be a typhoon. Sea surface temperatures in this area are high enough for tropical cyclones or typhoons to develop, and they are expected to continue to develop.



Looking at the weather map for the coming week, a "low" mark can be seen over the sea south of Japan from around the 30th (Saturday). It is expected to gradually move northward, and may approach Japan from the end of May to the beginning of June.

As of 8 a.m. today, the 26th, no typhoon information has been announced yet, but depending on future forecasts, it could have a major impact on the weather around Japan. Please pay attention to the latest information that will be updated in the future.

Weekly weather: Widespread rain due to fronts and low pressure; watch out for new typhoons in the future

2026/05/26 07:18

From now on, there will be widespread rain and strong winds in some places due to the influence of fronts and low pressure systems. Additionally, it is expected that another typhoon will form in the ocean far south of Japan.



Tomorrow, the 27th (Wednesday), there will be widespread rain mainly in western Japan due to the influence of a low pressure system and front moving from the west. As warm, humid air flows toward the low pressure system and front, atmospheric conditions will become extremely unstable, and there is a risk of warning-level heavy rain in southern Kyushu into the 28th (Wednesday). Please pay attention to the direction of the rain and be careful of landslides, flooding of low-lying areas, and rising river waters.

A new low pressure system is expected to form in the Sea of Japan on the 28th (Wednesday). The rain has spread to eastern and northern Japan, and there is a possibility of stormy weather in northern Japan on Friday the 29th due to stronger winds around the low pressure system. In addition to the increasing rain, please be careful of strong winds and high waves.

On the 30th (Saturday), the area around Honshu will be covered by a belt-shaped high pressure system, and many places will be sunny. It will be hot and humid in many places, with midsummer days exceeding 30 degrees Celsius. Depending on the location, there may be extremely hot days with temperatures exceeding 35 degrees Celsius. Please take proper measures against the heat to avoid heat stroke.

There is a possibility that a new typhoon will form in the sea far south of Japan by around 21:00 on the 27th (Wednesday). It is expected to gradually move northward, and could have a major impact on the weather around Honshu from the end of the month to the beginning of June.
No typhoon information has been announced at this time, but please pay attention to future information.

There is a risk of a linear rain band forming in the Amami region from early morning until noon on the 26th. be careful

2026/05/25 18:36

In the Amami region, a linear rain band will form from early morning until noon on the 26th, and the risk of heavy rain disasters may increase rapidly. Please be careful of landslides, flooding of low-lying areas, and rising river waters in the Amami region until the 26th. Also, be wary of lightning, tornadoes, and other strong wind gusts.



In the Amami region, heavy rain or very heavy rain with thunder will fall until noon on the 26th, leading to heavy rain in some places. It is possible that the rain will continue after that.
The predicted 24-hour precipitation from 18:00 on the 25th to 18:00 on the 26th is expected to be 150 mm

#Amami region.

If a linear precipitation band occurs, there is a risk of further rainfall locally.



If there are signs that a developed cumulonimbus cloud is approaching, please take precautions such as moving inside a building.

Today, the 25th (Monday) Weather forecast: Sunshine is shining in many places, but be careful of sudden heavy rain in Okinawa

2026/05/25 12:29

The afternoon of today, the 25th (Monday), is expected to be sunny in many places from Hokkaido to Kyushu. There is a chance of showers, but they are likely to be limited to areas along the mountains. However, the atmospheric conditions in Okinawa continue to be unstable, and you need to be careful about sudden strong rain and thunderstorms.



Today, the 25th (Monday), in the afternoon, it will be mostly sunny over a wide area from northern to western Japan, gently covered by high pressure.
However, from Kanto to Kyushu, there will be showers in the afternoon, mainly along the mountains, but the rain is expected to be short-lived and not strong.
Meanwhile, Okinawa and Amami will continue to experience unstable atmospheric conditions as the rainy season front extends. Be careful of lightning and sudden heavy rain. Particularly in the main island of Okinawa, there will be locally heavy rain.



In areas west of the Tokai region, there are midsummer days where the maximum temperature is over 30 C, with temperatures reaching 33 C in Kurume City, Fukuoka Prefecture and Hita City, Oita Prefecture, 32 C in Saga City, and 31 C in Osaka City and Nara City.In Kanto, Hokuriku, and Tohoku, there are also places expected to approach 30 C, mainly inland.

Also, there are some places, especially in the Kanto and Tohoku regions, where the difference in experience compared to the previous day is significant. It will suddenly get hot, so please be careful not to get sick.

Rainy season front stagnates; warning-level heavy rain is likely to occur on Okinawa main island; be careful of heavy rain disasters

2026/05/25 07:49

The rainy season front is extending from northern China to the Nansei Islands, extending to the south of Japan. In the main island of Okinawa, atmospheric conditions are extremely unstable due to the rainy season front and moist air flowing into the front, so there is a risk of warning-level heavy rain in the south-central and northern parts of the main island today, the 25th, depending on the degree of rain cloud development.



[Rain Forecast]
+Precipitation expected for 1 hour today, 25th (in places with the most)
Central southern part of the main island 20mm
Northern main island 30mm
+24-hour precipitation expected by dawn on the 26th tomorrow (in places with the most)
Central-southern main island 40mm
Northern main island 60mm

[Disaster prevention matters]
In the northern part of the main island, active rain clouds associated with the rainy season front are likely to form today, the 25th, and heavy rain of 30 mm or more per hour is expected in some places. In the central and southern parts of the main island and the northern part of the main island, there is a risk of warning-level heavy rain depending on the degree of rain cloud development, so careful attention should be paid to landslides, flooding of low-lying areas, and rising river waters.
Also, the atmospheric conditions in the main island of Okinawa will be unstable through tomorrow, the 26th, so please be careful of lightning, tornadoes, strong gusts of wind, and sudden heavy rain.

Weather for today, the 25th (Monday): Sunshine reaches a wide area; rainy season continues in Okinawa

2026/05/25 06:20

Today, the 25th (Monday), the area around Japan is expected to be covered by a mobile anticyclone. The sun is shining widely and temperatures are expected to rise. On the other hand, in Okinawa and Amami, the rainy season will continue and there will likely be periods of rain.



In the morning, there will be some lingering rain in Hokkaido, mainly in eastern Hokkaido, but the weather will gradually improve. It looks like the sun will return from the Sea of Japan side in the afternoon.

Tohoku to Kyushu will be covered by high pressure, so sunlight will reach a wide area. The weather will be sunny during the day, and the temperature will rise in many places compared to the previous day (24th), with temperatures likely to reach around 30c in many places. In Tohoku and eastern Japan, the temperature difference from the previous day is large, so please take care of your health.

In the Nansei Islands, the rainy season front will remain stationary and the weather will be prone to rain. Please be careful as there is a risk of heavy rain and thunderstorms in Amami and the main island of Okinawa.

[Starting soon] New weather disaster prevention information begins [Landslide edition]

2026/05/24 18:41

Starting from late May, the weather and disaster prevention information system that is directly connected to our lives will be significantly updated.
In the new information, the degree of disaster risk is shown as "level + number", and the color coding is unified, making it easier to make evacuation decisions.



#This change will be applied to the following four disasters.
+Heavy rain
+River flooding
+Landslide disaster
+Storm surge
This article will focus on the changes in landslide information.



#Conventional issues
Previous landslide information had the following difficulties in understanding.
+The names are different depending on the level, such as "warning" and "warning information"
+Indicators are not unified, such as the soil rainfall index for levels 2, 3, and 5, and the soil rainfall index + 60-minute rainfall for level 4



It was pointed out that these points could lead to confusion among residents in response to information and
delays in evacuation decisions.

#Points to be improved with the update
+The alert level is clearly stated at the beginning of the information,
+Evacuation behavior becomes easier to intuitively understand
+Unification of names
+Unification of indicators for announcements

#Standards for level 3 equivalent information have changed significantly
Previously,
many "heavy rain warnings (landslides)" equivalent to level 3 were announced,
There were many misses = low accuracy rate.

From now on,
will be announced as level 3 when it is expected that the standard for level 4 will be reached within 3 hours.
This is expected to significantly reduce the number of Level 3 presentations that do not reach Level 4
/improve the accuracy rate
.



On the other hand, changes are also expected, such as
+The time from level 3 to level 4 will become shorter
+There will be more cases of level 4 being announced without going through level 3
.
For this reason, it is important to check weather information more frequently than ever before to understand the
situation.




#What's important is "color" and "level"
+What color is at which level
+What actions should be taken at each level
Just understanding this will greatly change your actions in an emergency.



Please use the new weather disaster prevention information to take early evacuation actions.

Tomorrow, the 25th (Monday), the weather will improve around Honshu, and the next day the weather will be downhill from the west.

2026/05/24 12:36

Tomorrow, the 25th (Monday), the area around Honshu will be covered in high pressure, and the weather is expected to generally improve.



There will be some lingering rain in Hokkaido in the morning, but it will gradually stop.
Meanwhile, the front is stationary near the Okinawa region, and rain is expected to continue.
The ground has become loose in some areas due to the rain since the weekend, so please be careful of landslides.



The sunshine will return near Honshu and the temperature will rise.
In the evening, there is a possibility of showers along the mountains on the Pacific side and inland areas of the Chugoku region and northern Kyushu.
When going out, it is a good idea to bring a folding umbrella just in case.

The next day, the 26th (Tuesday), a low pressure system accompanied by a front from the Yellow Sea will move eastward, and the weather is expected to turn downward from the west.





The rain will gradually spread into eastern Japan into Wednesday.

The coming week is expected to continue to be cloudy due to low pressure and fronts.



Please check the latest weather forecast before going out.