A low pressure system develops, warning of heavy rain disaster from western to eastern Japan from tomorrow 4th (Sunday)

2026/05/03 09:04

A low pressure system accompanied by a front is moving east-northeast across the Yellow Sea. This low pressure system will move east-northeast across the Sea of Japan until tomorrow, the 4th (Monday), and the front will pass from eastern Japan to the Nansei Islands. Atmospheric conditions are expected to become extremely unstable in some places as warm, humid air flows toward low pressure systems and fronts.

For this reason, rain clouds are likely to develop from western Japan to eastern Japan, and there is a risk of heavy rain accompanied by localized thunderstorms. Additionally, there is a risk of extremely heavy rain of more than 50 mm per hour, mainly on the Pacific side of western Japan, today, the 3rd.




#Expected amount of rain (in areas where there is a lot)
+24-hour precipitation expected by dawn on the 4th (Monday) tomorrow
Hokuriku region 100 mm
Kinki region 15 0mm
80mm

#Disaster Prevention Matters
From eastern Japan to western Japan, caution and vigilance are required for landslides, flooding of low-lying land, and rising river waters from tomorrow 4th (Monday). Also, be careful of strong wind gusts such as lightning and tornadoes.
If there are signs of a developing cumulonimbus cloud approaching, please take steps to ensure your own safety by moving inside a building. There is also a risk of hail, so care must be taken when managing crops and agricultural facilities.

Today's weather on the 3rd (Sunday) Rain clouds are expanding from the west. Be careful of heavy rain from western Japan to eastern Japan.

2026/05/03 06:21

Today, the 3rd (Sunday), which is Constitution Day, a low pressure system accompanied by a front will move toward the Sea of Japan. The weather is expected to go downhill from the west near Japan, with rain expected to fall in the Kanto region and other areas at night. In northern Japan, the rain is more likely to fall later in the day, so it's likely to be a day when umbrellas will be useful over a wide area.



It will rain in Kyushu from the morning due to the effects of low pressure and fronts. Rain is expected to start in Chugoku, Shikoku, and Kinki around noon.
After the evening, the area of rain will spread to eastern Japan, and it is expected to rain in the Tokai and Hokuriku regions from the evening, and in the Kanto region at night. Even if it's not raining when you go out, please prepare rain gear in time for your return.
Also, atmospheric conditions will be unstable in the afternoon as moist air flows towards the low pressure system. Rain clouds will develop mainly on the Pacific side, and there is a risk of extremely heavy rain of over 50mm per hour. Please be careful of landslides and flooding of low-lying areas.

In northern Japan, clouds tend to spread around the Sea of Japan, and the weather is not clear. After the evening, the area of rain will expand from the Sea of Japan side, and there will be periods of sunlight in the morning, and there will be places on the Pacific side where it will start to rain at night. If you are returning home late, it is a good idea to have a folding umbrella.

The temperature will be lower than the previous day in many places, mainly from western Japan to eastern Japan, but it is likely that the temperature will be typical for this time of year in many places. Even in northern Japan, it will be as warm as normal. Please be careful about the temperature difference throughout the day.

[General weather information] May 3rd to 4th: Be careful of heavy rain, thunder, and gusts of wind

2026/05/02 17:22

The Japan Meteorological Agency has released its first general weather information regarding heavy rain, lightning, and gusts.

A low-pressure system with a front near Central China is expected to move east-northeast across the Sea of Japan from the 3rd to the 4th, and the front is expected to pass from eastern Japan to the Nansei Islands.
Atmospheric conditions will be extremely unstable in some places as warm, humid air flows towards low pressure systems and fronts.



From the 3rd to the 4th, from eastern to western Japan, please be careful of landslides, flooding in low-lying areas, and rising river waters.
Also, be careful of lightning, tornadoes, strong gusts of wind, and hail.



# Rain forecast
24-hour precipitation from 18:00 on the 3rd to 18:00 on the 4th (in areas with the most)
Hokuriku region: 100 mm
Kinki region: 150 mm
Okinawa region: 80 mm

# Disaster prevention precautions
From eastern Japan to western Japan, please be careful of the following points from the 3rd to the 4th.
+Landslides, flooding of low-lying areas, rising river levels
+Severe gusts caused by lightning strikes, tornadoes, etc.
+Damage to crops and agricultural facilities due to hailstorms

+If there are signs that a developed cumulonimbus cloud is approaching (suddenly darkening of the sky, hearing thunder, sudden cold wind blowing, etc.), prioritize safety by moving inside a building.

May 2nd (Saturday) Summer days continue, temperature in Tokyo similar to late July

2026/05/02 12:39

A low pressure system is located over the ocean south of Hokkaido and is moving northeast.
This low pressure system is expected to move toward the Kuril Islands area through the night, and Hokkaido will experience rainy and cloudy weather. On the other hand, from the Tohoku region to western Japan, plenty of sunlight is expected to fall, and temperatures are expected to rise rapidly.

It will be a summer day over a wide area, with the maximum temperature expected to be 28c in Tokyo and 26c in Nagoya and Kagoshima.



It will be unusually hot for May, and the risk of heat stroke will increase as the body is not yet accustomed to the heat. Basic measures such as hydrating frequently, taking adequate breaks, and wearing a hat when going out are essential.



Many people go outdoors during the holidays, and the elderly and children are especially susceptible to the effects of the heat, so it is important for those around them to be careful. If you notice anything unusual, please seek medical attention immediately.

Tomorrow, the 2nd (Saturday), the rain will reach northern Japan. Be careful of lightning and stronger winds.

2026/05/01 19:39

Currently, there is a low pressure system with a front in the Sea of Japan, and it is moving east-northeast. This low pressure system will continue to develop as it passes near northern Japan and will continue toward the waters near the Chishima Islands through the morning of Saturday the 2nd.



Today, the 1st (Friday), rain is falling over a wide area from western Japan to northern Japan due to the influence of a low pressure system. Atmospheric conditions continue to be unstable as strong cold air is flowing into the sky for this time of year.

In Kitaibaraki, Kitaibaraki City, Ibaraki Prefecture, extremely heavy rain of 61.0 mm was observed in the hour up to 12:42, in Maizuru City, Kyoto Prefecture, 45.0 mm in the hour up to 14:44, and in Hirono, Hirono Town, Futaba District, Fukushima Prefecture, heavy rain of 40.0 mm was observed in the hour up to 13:29.
Also, due to the influence of the low pressure system, the gradient of atmospheric pressure is increasing, and the winds are increasing mainly in coastal areas.



The area of rain is gradually expanding to northern Japan. Tomorrow, the 2nd (Saturday), the weather is expected to improve as a high-pressure system approaches from the west, but rain is expected to continue in some places in northern Japan into the morning.
Even if the weather improves, there is a large pressure gradient between the low pressure system and the high pressure system moving from the west, and strong winds will continue in many areas, so please be careful when going out.

Please be careful of thunderstorms, tornadoes, severe gusts of wind, hail, and sudden heavy rain in the Tohoku and Hokuriku regions from tomorrow, the 2nd (Saturday) until dawn.
Also, very strong winds are expected to blow from the west in the Tohoku region. Please be on guard for traffic disruption and damage to buildings due to strong winds from early morning until evening on the 2nd (Saturday).

[Wind Forecast]
Maximum wind speed (maximum instantaneous wind speed) expected on the 2nd (Saturday)
Tohoku Sea of Japan side 20 meters (30 meters) over the sea
Tohoku Sea of Japan side On land 18 meters (30 meters)
Tohoku Pacific side Sea 20 meters (30 meters)
Tohoku Pacific side Land 18 meters (30 meters)

May starts with rough weather. Even if the rain stops, be careful of sudden heavy rain and lightning strikes.

2026/05/01 06:48

Today, Friday, May 1st, a low pressure system accompanied by a front will pass near Honshu. It will rain over a wide area from western Japan to eastern Japan, and the wind will be strong and the weather will be rough. In the afternoon, even in areas where the rain has stopped, there is a risk of sudden rain or thunderstorms, so please be careful.





If you look at the rain cloud radar at 6am, you can see that active rain clouds are hanging over the Tokai and Kanto areas. In the Pacific side of eastern Japan, including the Tokai and Kanto regions, the rain will intensify, especially in coastal areas, and there is a risk of heavy rain accompanied by thunder into the afternoon. Please be careful of flooding of low-lying areas, landslides, and rising river waters due to heavy rain, and be aware of the impact on transportation.



The rain may stop in some areas in the afternoon, but strong cold air will flow into the sky for this time of year. Looking at the probability of lightning, the probability of lightning occurring is high mainly in inland areas from western Japan to eastern Japan, and areas with high probability are expected to gradually move eastward. Around 6:00 p.m., there are some places near the Tokai region where the probability of lightning striking is close to 90%.
Today, even if the rain stops in the afternoon, there is a risk of sudden rain or thunderstorms. Please be aware of sudden changes in the weather, as there is a risk of lightning, tornadoes, strong wind gusts, and hail.



In northern Japan, it will gradually rain from evening to night, and the wind will become stronger, resulting in rough weather. There is a risk of heavy rain accompanied by localized thunderstorms, so please be careful of flooding of low-lying land and rising river levels due to heavy rain. In addition, there is a risk of extremely strong winds blowing in Tohoku into the second day of tomorrow, so please be careful of strong winds and high waves, especially in coastal areas.

One month forecast: High temperatures will trend nationwide after Golden Week; signs of rainy season in Okinawa and Amami

2026/04/30 20:41

On the 30th (Thursday), the Japan Meteorological Agency announced the latest monthly weather forecast for the next month.



According to the prediction results of the numerical forecast model, the average sea level pressure for one month will be lower than normal in the north of Japan, and low pressure will likely pass north of Japan more easily. On the other hand, there is a trough of weak atmospheric pressure near Honshu. Temperatures at around 1,500 meters above the ground tend to be higher than normal, and the whole country is likely to be covered in warm air.



From now on, the weather in northern Japan will change every few days, but it will be less affected by low pressure systems and fronts, and there will be more sunny days than normal. Precipitation is expected to remain at almost normal levels.
Similarly, the weather from eastern to western Japan is expected to change every few days, and the amount of precipitation and sunshine hours during this period are expected to remain roughly at normal levels.

However, the average temperature will be higher nationwide. After Golden Week ends, there is a strong possibility that temperatures will be higher than normal, mainly in western and eastern Japan, and it is expected to become hot until late May. It will be a summer day with temperatures above 25 degrees Celsius, and depending on weather conditions, some places may even record midsummer days with temperatures above 30 degrees Celsius. To avoid heatstroke, be sure to take precautions against the heat, such as drinking plenty of water and taking regular breaks.

Okinawa/Amami is susceptible to fronts and humid air, and many cloudy and rainy days are expected. In normal years, the rainy season starts around May 10th in Okinawa and around May 12th in Amami. It looks like the rainy season is gradually approaching. Around mid-May, there may be a period when the weather is temporarily less affected by fronts and humid air, but towards the end of May it will again be susceptible to the influence of humid air.
Precipitation is expected to remain at about the same level as usual, but the rain may become heavier at times, so it would be safer to take measures for heavy rain early.

[General weather information] May 1st (Friday) to May 2nd (Saturday) Be careful of lightning, gusts, and sudden strong rain

2026/04/30 18:40

A low pressure system accompanied by a front is located south of Kyushu and is moving east-northeast.
This low-pressure system is expected to move from the Pacific side of western Japan to the Pacific coast of eastern Japan through Friday, May 1st, and proceed as far as the coast of Sanriku on the night of the 1st.
Meanwhile, another low pressure system is expected to form off the coast of Sanin by the morning of the 1st (Friday) and reach the Sea of Japan side of eastern Japan by the evening of the 1st (Friday).


Also, on the 1st, strong cold air is expected to flow into the skies near Honshu with temperatures below -21 degrees Celsius for this time of year. As a result, atmospheric conditions will be extremely unstable from western Japan to eastern Japan.
As a result of this, stormy weather with thunder is expected over a wide area from eastern Japan to western Japan, and if rain clouds develop more than expected or if the developed rain clouds continue to cover the area, there is a possibility of warning-level heavy rain.


Currently, weather information regarding general weather information
regarding lightning, gusts and hail has been announced.

#Period to be careful
Western Japan: From tomorrow 1st (Friday)
Eastern Japan: From tomorrow 2nd (Saturday)

Please be careful of thunderstorms, tornadoes, severe gusts, and sudden heavy rain. If there are signs that a developed cumulonimbus cloud is approaching, please take precautions such as moving inside a building. If cumulonimbus clouds develop, there is a risk of hail, so please be careful when managing crops and agricultural facilities.

There is a risk of heavy rain during commuting hours tomorrow, so be careful of unstable atmospheric conditions.

2026/04/30 12:47

A low-pressure system accompanied by a front is moving eastward over the East China Sea, and it is already raining over a wide area of western Japan. Rainfall is increasing on the Pacific side of Shikoku and Kyushu, as well as in Okinawa Prefecture.

Today, the 30th, the low pressure system is expected to move east along the southern coast of Honshu. In western Japan, it rains easily throughout the day, so you won't be without your umbrella. The area of rain is expected to gradually spread eastward, with rain expected to begin in the evening in the Tokai region and in the Kanto region from night.



Tomorrow, the low pressure system is expected to move further south of Honshu and east of Japan. Additionally, strong cold air for this time of year is expected to flow from eastern Japan to the Kinki region at an altitude of approximately 5,500 meters. As a result, atmospheric conditions are expected to be extremely unstable in eastern Japan from early morning until late at night.



It will be a rainy day, mainly from northern Japan to eastern Japan, and if rain clouds develop more than expected, or if the developed rain clouds continue to hang around for a long time, there is a risk of warning-level heavy rain on the Pacific side.

From the Tohoku region to the Tokai region on the Pacific side, rain is likely to peak on the morning of tomorrow 1st. There is a risk of heavy rain during commuting hours, and transportation may be affected. Please act with plenty of time.

Temperatures in western Japan are similar to those of March; in northern Japan there is a large difference in temperature throughout the day.

2026/04/30 06:46

Today, the 30th (Thursday), it is expected to rain throughout the day in western Japan due to a low pressure system. The weather is expected to go downhill in eastern Japan as well, with the sky likely to be cloudy.



For this reason, from western Japan to eastern Japan, the rise in temperature is slow even during the day, and the temperature is lower than the day before, with most places having a maximum temperature of less than 20c. Temperatures are expected to be similar to late March, mainly in western Japan. It can feel cool during the day, so it's a good idea to wear a jacket or something when you go out.

On the other hand, northern Japan is sunny and sunny. As relatively warm air flows in, temperatures are likely to rise, and daytime temperatures are expected to be similar to mid-to-late May. It gets colder in the morning due to radiation cooling, so please be aware of the differences in temperature throughout the day, such as adjusting your clothing accordingly.

The predicted maximum temperature in each region is Sapporo 18c, Sendai 17c, Tokyo 18c, Nagoya 17c, Kanazawa 19c, Osaka 18c, Kochi 18c, and Fukuoka 17c.