Be careful of sudden rain and lingering heat on Monday the 17th; temperatures are rapidly increasing in the Kanto region

2026/08/17 07:37

Today, the 17th (Monday), which marks the end of the Obon holiday for many people, the sun will shine in northern Japan, but clouds are expected to spread over wide areas in eastern and western Japan.

Due to the influence of moist air and pressure troughs from the Pacific Ocean side, it is easy to rain in southern Shikoku and the Chugoku region,
There is also a possibility that it may rain locally from Kanto to Kyushu. You need to be careful about sudden changes in the weather.
Just in case, it's a good idea to bring a folding umbrella.




Also, as warm air flows in from the south, daytime temperatures in the Kanto region will be significantly higher than yesterday.
Western Japan is also expected to continue experiencing a very hot and humid summer.

From here on out, clouds are likely to spread across northern and western Japan due to the influence of humid air, and the humid, oppressive heat will continue.



To avoid getting sick early after the holidays,
please take precautions against heatstroke, such as by drinking water frequently.

17th (Monday): Heavy rain possible from northern Kyushu to western Japan; caution due to stagnant shear line

2026/08/16 22:42

A low pressure system is moving northeast near the Korean Peninsula.
Currently, there are active rain clouds near the Tsushima Strait.



This low pressure system is expected to move toward the vicinity of Primorye on the night of the 18th (Tuesday).
Warm and humid air is flowing towards the low pressure system, causing unstable atmospheric conditions in the area.

Also, a sheer line extending from the low pressure system will extend over northern Kyushu,
tomorrow, the 17th (Monday), clouds will likely spread mainly over western and eastern Japan, and showers and thunderstorms are likely to occur in places.
Although there will be periods of sunshine in northern Japan, it is expected to rain in Sendai at night.



There is a risk of active rain clouds forming in northern Kyushu and western Japan tomorrow.
There are likely to be heavy rain in Iki, Tsushima, and Goto in Nagasaki into Monday.



If rain clouds continue, the risk of landslides, flooding of low-lying land, and rising river waters will increase.
Please check the weather forecast in your area and be careful of sudden weather changes.

Today, the 16th (Sunday), watch out for heavy rain with localized thunderstorms in eastern and western Japan.

2026/08/16 12:54

Today, the 16th (Sunday), a low pressure system is moving east-northeast across the Yellow Sea. It is expected to move toward the Sea of Japan tomorrow, the 17th (Monday).
Also, there is a high pressure system east of the Kuril Islands, which extends from northern Japan to eastern Japan.



Currently, it is raining in some places in Chiba Prefecture, the Kinki Pacific side, Shikoku, and northern Kyushu due to the influence of easterly winds from the ocean around the edge of the high pressure system and warm, humid air flowing into the low pressure system.



After this, the low pressure system will move northeast, so rain will spread over Kyushu, Chugoku, and Shikoku.
Especially in northern Kyushu, warm, humid air is flowing toward a low-pressure system, making atmospheric conditions unstable. Heavy rain is expected to occur in Iki, Tsushima, and Goto in Nagasaki Prefecture until noon tomorrow, Monday, the 17th, with extremely heavy rain accompanied by localized thunderstorms. If the rain clouds develop more than expected, there is a risk of warning-level heavy rain.
Please be careful of landslides, flooding of low-lying areas, and rising and flooding rivers.

Also, in Kochi Prefecture, heavy rain is expected to occur in the afternoon, accompanied by thunder, as southeasterly winds that flow into a low-pressure system blow in from the sea.

There will be places in the Kanto and Hokuriku regions where it will rain due to the damp air.
In Hokuriku, due to the effects of moist air and a trough in the atmospheric pressure above, heavy rain with thunder is expected to continue to fall in some places until tonight.
Be careful of lightning and gusts of wind.

Weather for today, the 16th (Sunday): Rain in places from Kanto to Kyushu

2026/08/16 06:54

It is expected that moist air will continue to flow in from a tropical cyclone and an anticyclone centered east of Hokkaido. Although the cold air in the sky is weakening and the rain is not expected to be as heavy as it has been for several days, please be careful of sudden rain in various places. Additionally, due to the influence of a low pressure system near the Korean Peninsula, clouds will likely spread over western Japan, and it will rain in places.



Clouds are expected to spread over Kyushu due to the influence of a low pressure system approaching from the East China Sea. There will be temporary rain mainly on the East China Sea side near the low pressure system. It's safe to have an umbrella when you go out. Due to less sunlight, daytime temperatures will be lower than yesterday, with many places likely to reach around 30 degrees Celsius. It will feel a bit hot and humid due to the high humidity.
Atmospheric conditions from Chugoku/Shikoku to Kanto become unstable due to the influence of humid air. It will be a day when clouds will spread easily, and rain clouds are expected to form and develop mainly on the Pacific side of Shikoku and Kinki. In eastern Japan, there are times when the sun can reach you. Although there will be no extreme rise in temperature due to the abundance of clouds, there will be some places where the temperature will exceed 30c during the day.
Northern Japan is expected to be covered in high pressure, and blue skies are expected to spread around the Sea of Japan side. There will be a lot of clouds on the Pacific side as moist winds blow in. In the morning, temperatures will drop mainly in inland areas, making the weather pleasant. However, once the sun shines through, the temperature will rise, and midsummer days are expected to reach over 30 degrees Celsius on the Sea of Japan side of Tohoku and inland Hokkaido. Please be careful about what you wear as the temperature can vary greatly throughout the day.

Weather for tomorrow, the 16th (Sunday): The last day of Obon will be sunny in northern Japan. The sky will be dominated by clouds from eastern to western Japan.

2026/08/15 18:05

Tomorrow, the 16th (Sunday), the last day of Obon, will be covered in high pressure centered east of the Kuril Islands, and many places in northern Japan will be sunny. It looks like it will be a day with clouds spreading easily from eastern to western Japan.



In northern Japan, there will be many sunny places, especially on the Sea of Japan side. Clouds will spread out on the Pacific side, but the sky is likely to be sunny with periods of sunshine. Temperatures tend to rise on the Sea of Japan side due to humid easterly winds, and in some places the temperature will approach an extremely hot day. Please be careful of heat stroke.

The sky will likely be cloudy from eastern Japan to western Japan due to the influence of humid air. Although there are periods of sunshine in eastern Japan, you need to be careful of localized heavy rain. It's a day covered in thick clouds in western Japan. It would be safe to have a folding umbrella when going out. In addition, active rain clouds are likely to form in northern Kyushu. Please bring a large umbrella when going out.

Tomorrow, the 16th (Sun), the moon approaches Venus. Observe the "Evening Star"!

2026/08/15 17:39

After sunset on the 16th (Sunday), the slender Moon with an age of 3.4 will approach Venus in the western sky. Why not take a look at the bright, slender Moon and Venus

Venus orbits inward of the Earth in the solar system, so it can only be observed at dawn and sunset. For this reason, it is called the ``morning star'' and ``evening star.'' Today, the 15th (Saturday), its apparent position as seen from Earth will be the farthest from the Sun, at the greatest eastern elongation, and it will shine extremely brightly in the western sky. For this reason, it can be seen even when the sky is still bright.



The image shows the sky west of Tokyo 30 minutes after sunset on Sunday the 16th.
The thin moon and Venus shine as if they were close together. You can also see the first-magnitude star Spica in the constellation Virgo nearby.



Now, let's take a look at the weather distribution forecast around sunset on the 16th (Sunday) tomorrow.

Northern Japan is expected to be mostly sunny. This is a chance for stargazing.

Eastern Japan is likely to have areas where clouds tend to spread as moist air flows in around the edge of the high-pressure system near the Chishima Islands. You might also try aiming for gaps in the clouds.

Western Japan will experience rain in some places as warm, humid air flows in due to the low pressure system expected to move from the Yellow Sea to the Sea of Japan. Unfortunately, stargazing may be difficult.

Okinawa will probably have some clouds in some parts, but it will mostly be sunny.

Why not try stargazing on the last day of Obon vacation or as a memory of your summer vacation

Sea surface temperature drops due to Typhoon No. 13 [Ocean summary (August 2, 2026 - August 8, 2026)]

2026/08/15 17:15

Sea surface temperatures continued to be higher than normal on the Sea of Japan side, and on the Pacific side, where Typhoon No. 13 passed, were around normal or slightly lower than normal.

Below is a summary of the ocean (August 2, 2026 - August 8, 2026)



#Pressure distribution and waves
On the 2nd, Typhoon No. 13 moved west-northwest around Minamitorishima with very strong force, causing waves to rise around the typhoon. On the 3rd, Typhoon No. 13 moved westward near Ogasawara, causing waves to rise to around 2.5 meters in height on the Pacific side of eastern Japan. From the 4th to the 6th, Typhoon No. 13 moved westward from the south of Japan, causing wave heights to rise to 3 to 4 meters across a wide area on the Pacific side. On the 6th, the wave height was around 5m near the Nansei Islands. From the 7th to the 8th, large typhoon No. 13 approached and passed the main island of Okinawa while maintaining extremely strong strength. On the 7th, in Amami and Okinawa around the typhoon, the wave height was over 10 meters in some places, and it was very strong. On the 8th, waves were extremely strong in the Sakishima Islands with a height of around 9 meters.



#Sea surface temperature
In Japan's waters, areas with higher-than-normal temperatures have expanded compared to last week, with temperatures in the western region reaching a maximum of 4 C above normal. In the East China Sea and the waters near the Nansei Islands, the area of higher-than-normal waters shrank toward the latter half of the period, but it remained slightly higher than normal. Continuing from the previous week, the areas above normal in the Kanto and Sanriku offings and off the southeastern coast of Hokkaido continued to shrink, and the sea levels were at or slightly below normal. In the waters near the Kuril Islands and the Sea of Okhotsk, areas with higher-than-normal temperatures expanded toward the latter half of the period. In the waters around the Kuril Islands, the maximum temperature was 3 C above normal.

The sky continues to be unstable in the Kanto region. Be careful of sudden changes in the weather in the afternoon as well.

2026/08/15 12:24

The atmospheric conditions have been unstable in the Kanto region since yesterday, where moist air is flowing in around the edge of a high-pressure system centered near the Chishima Islands.

Kesa also started to fall intensified from dawn to dawn, with heavy rain of 39.0mm/h observed in Kisarazu City, Chiba Prefecture, and 32.0mm/h in Ome City, Tokyo.



Although the rain clouds have calmed down compared to Kesa, as of 12:00, rain clouds are still forming in some places in the Kanto region. Similar conditions will continue into the afternoon, with the weather expected to be sunny but changeable. It's safe to carry a folding umbrella when you go out.



Also, even a small amount of rain could cause landslides in areas where the ground has become loose due to previous rains, especially in Chiba Prefecture, which experienced heavy rain the other day. If you are involved in restoration work or live near a slope, please be careful and monitor the future movement of rain clouds.

Weekly weather: The Pacific high pressure system is gradually gaining strength, and the severe heat is likely to return gradually.

2026/08/15 07:26

From next week onwards, the Pacific high pressure system will gradually become more prominent near Japan. As a result, the severe heat will gradually return.





From tomorrow the 16th to the 17th, a low pressure system will approach from the west and move toward the Sea of Japan. Due to the influence of warm, humid air moving toward a low pressure system, rain and thunderstorms will occur in some places, mainly on the Sea of Japan side of western Japan, and localized rainfall will become stronger.
The Kii Peninsula and Shikoku are also expected to experience rain tomorrow, the 16th, due to the influence of moist air circulating around the edge of a high-pressure system. There is a possibility of heavy rain accompanied by thunder in Kochi Prefecture, so please be careful about how the rain falls.

On the 18th and 19th, it is expected that there will be temporary rain in northern Japan due to the effects of a low pressure system moving near the continent and a front extending from the low pressure system. There are also likely to be localized rain and thunderstorms in eastern and western Japan, mainly along mountains and inland. Even in areas where the weather forecast does not indicate rain, please be aware of sudden changes in the weather in the afternoon.

Around the 20th and 21st, a low pressure system will move across the Sea of Japan. Rain is likely to fall mainly from northern Japan to western Japan on the Sea of Japan side.

From now on, clouds will likely spread across the country due to the influence of humid air. Temperatures will continue to rise with the expansion of the high pressure system, and some areas are expected to experience extreme heat. As the days are expected to continue to be humid and humid, please prevent heat stroke by hydrating properly, replenishing salt intake, and using the air conditioner both day and night.

Weather forecast for today, the 15th (Saturday): Clouds are likely to spread across the country. Be careful of sudden rain and thunderstorms in the afternoon.

2026/08/15 06:46

Today, the 15th (Saturday), clouds are likely to spread around Honshu due to the influx of moist air around the edge of the high pressure system, and there are likely to be localized rain and thunderstorms in the afternoon from Tohoku to Kyushu.



As of 6 a.m., active rain clouds can be seen near Kanto-Koshin and the Kii Peninsula, and there are places where it is raining. In Saitama Prefecture, there are some areas where a level 4 landslide warning has been issued, so please be on alert for landslides in the morning. In other areas of the Kanto-Koshin region, there are places where there will be light showers in the afternoon, and the ground may be loose in some places due to previous heavy rains, so please be careful of landslides even if there is less rain than usual.



From Tohoku to other areas of Kyushu, the weather will be changeable in the afternoon. It is necessary to be careful about sudden rain and thunderstorms, especially in the Hokuriku, Tokai, and Koshin regions, where there is a high probability of lightning occurring in the afternoon, and there is a possibility of locally heavy rain. Please be careful of flooding of roads and sudden rise in river water due to short periods of heavy rain.