El Nino monitoring bulletin: El Nino phenomenon is likely to occur into the summer

2026/05/13 16:27

On the 12th (Tuesday), the Japan Meteorological Agency announced the latest El Nino monitoring bulletin.

Currently, conditions appear to be normal, with neither El Nino nor La Nina occurring, but the situation is approaching the characteristics of an El Nino. This trend is expected to gradually become more pronounced over the summer, increasing the likelihood of an El Nino phenomenon occurring.

#April Live Report
The difference in sea surface temperature in the El Nino monitoring area in April from the standard value was +0.7c, which was higher than the standard value. Additionally, the 5-month moving average used to determine the occurrence of El Nino and La Nina phenomena in February was 0.0 C, the same value as the standard value.

Convective activity remained almost at normal levels near the international date line in the equatorial Pacific Ocean. Additionally, the easterly winds (trade winds) in the lower atmosphere of the equatorial Pacific region remained strong until March, but have weakened to normal levels.

The above results indicate that although the conditions are normal, with neither El Nino nor La Nina occurring, the conditions are transitioning to the characteristics of an El Nino.



#Future outlook
According to the live report, warm water seen at the surface layer of the equatorial Pacific Ocean is moving eastward. The coupled atmosphere-ocean model predicts that this eastward movement of warm water will work to maintain sea surface temperatures in the central to eastern equatorial Pacific Ocean above normal, and that the eastward movement of warm water in the ocean surface layer, strengthened by the interaction between the atmosphere and the ocean, will continue.
As a result, the sea surface temperature in the El Nino monitoring area is predicted to rise through the fall and remain higher than the standard value.

Based on the above, we predict that there is a 90% or higher probability that an El Nino phenomenon will occur by summer.

#About the El Nino and La Nina phenomena
The El Nino phenomenon is a phenomenon in which sea surface temperatures rise above normal from the equatorial Pacific Ocean near the international date line to the coasts of South America, and this condition persists for about a year.
On the other hand, a phenomenon in which the sea surface temperature continues to be lower than normal in the same area is called a La Nina phenomenon.

When the El Nino phenomenon occurs, areas around Japan are statistically expected to experience cooler summers and warmer winters. However, the Japan Meteorological Agency predicts that there is a high possibility of high temperatures around Japan this summer, including the possibility of an El Nino phenomenon occurring.

13th (Wednesday) Temperatures are rising rapidly; thunderstorms along the mountains are expected to move south in the evening

2026/05/13 16:07

The temperature is rapidly rising during the day today, and I think there are many people who have gone beyond "sweating and cheerful" to feeling "sweating and cheerful."



As of 15:00 on the 13th,
the highest temperature of the year was observed at many locations.
Tajimi City, Gifu Prefecture 29.5c (highest this year)
Kiryu City, Gunma Prefecture 29.4c
Kita Ward, Okayama City, Okayama Prefecture 28.1c (highest this year)
Kyotanabe City, Kyoto Prefecture 28. 9c (this year's highest)
Nerima Ward, Tokyo 28.0c

On the other hand, there is strong cold air in the sky for this time of year
moving south, making the atmospheric condition extremely unstable.

It has been raining since this morning from Tohoku to Kinki and Shikoku, and many thunderstorms have been observed mainly along the mountains.
Rain clouds may move southeast into the evening and night.



Transportation may be affected depending on how it rains.
Please pay attention to the latest information.

Atmospheric conditions are unstable over a wide area today, the 13th (Wednesday); watch out for sudden changes in weather not only in inland areas but also in plains and urban areas.

2026/05/13 11:44

Looking at the rain cloud radar as of 11 a.m. today, the 13th (Wednesday), you can see that active rain clouds are forming in places in inland areas of eastern Japan.

Lightning has been detected in areas where active rain clouds are forming, and although the area is currently small, there is a possibility that the area where thunder clouds form will expand into the afternoon.



Today, the 13th (Wednesday), atmospheric conditions are expected to be unstable over a wide area around Honshu due to rising temperatures during the day, as well as cold air and moist air in the upper atmosphere. In particular, after noon, there are areas where there is a 90% chance of lightning occurring, such as inland areas and mountains in the Kanto-Koshin and Tokai regions. It is also expected that high probability areas will spread in the plains and urban areas, and the weather may change suddenly just as you are returning home.

Be careful of sudden thunderstorms due to sudden changes in weather from the afternoon to evening over a wide area from the southern Tohoku region to western Japan. Depending on the degree of development of rain clouds and thunderclouds, there is a risk of severe phenomena such as lightning, tornadoes, and hail, so please pay attention to changes in the sky.

From around the 16th this weekend, the warmth will approach midsummer, so be careful not to get heatstroke.

2026/05/13 11:42

From this weekend, around the 16th (Saturday), temperatures are expected to rise in many places, reaching 30c in some places. This is the time when you are not used to the heat yet, so please do not overdo it and take proper measures to prevent heatstroke.



The area around Japan is expected to be easily covered by high pressure from now on into the weekend. The weather will be sunny and the temperature will rise, with many days exceeding 20c in Sapporo, and many days exceeding 25c in Tokyo, which will be similar to June.
In Kofu, it is expected to be a midsummer day of 30c on the 17th (Sunday) and 31c on the 18th (Monday).
Nagoya and Osaka will also be as hot as 29c on the 17th (Sunday), approaching midsummer days.

The weather is expected to be hotter than usual, and your body has not yet gotten used to the heat, so you will need to take precautions against heatstroke. In particular, if you play sports or work outdoors, please take precautions such as taking frequent breaks and hydrating. Even if you are spending your time indoors, it is a good idea to use an air conditioner without overdoing it.



The Japan Meteorological Agency has announced early weather information regarding high temperatures for the period from May 17th (Sunday) to May 25th (Monday).
Extremely high temperatures are expected from Tohoku to Okinawa.
Early weather information regarding high temperatures is information that calls for caution at least 6 days in advance when the possibility of extremely high temperatures, which only occur once every 10 years, is higher than usual. Announced when the probability that the 5-day average temperature will be "considerably high" for the period 6 to 14 days ahead is 30% or more.

It looks like the high temperature trend will continue. It's a good idea to prepare early by doing light exercise such as walking to break up a sweat so your body can get used to the heat.

Weather for tomorrow 13th (Wednesday): Widespread atmospheric instability; be careful of sudden thunderstorms

2026/05/12 18:07

Tomorrow, the 13th (Wednesday), is likely to be a day where we will need to be careful about sudden changes in the weather, especially in inland areas and along the mountains.




A pressure trough with cold air in the sky is expected to pass near Japan. As a result, atmospheric conditions will become unstable over a wide area, especially inland and along mountains, leading to localized rain clouds and thunderstorms. Those who are going for leisure activities in the mountains should be careful of sudden strong rain, lightning, gusts of wind, and hail even if it is sunny.
Please be aware of changes in the sky when going out as rain clouds may roll in even in the plains.

There will be places in Hokkaido where it will rain temporarily. It's safe to have rain gear when you go out.

It looks like Okinawa will be closed during the rainy season.

Temperatures will be high in northern Japan, and in Hokkaido it will be as sunny as June. However, the temperature will drop after the rain clouds pass, so it's a good idea to wear clothes that are easy to adjust when going out. Temperatures from eastern to western Japan will be typical of this time of year. It looks like it will be a summer day in central Tokyo, with temperatures expected to reach 26 degrees Celsius.

Temperatures are rising in various places; unstable atmospheric conditions will continue into tomorrow, 13th (Sunday)

2026/05/12 13:38

Today, the 12th, a rainy season front extends from the Nansei Islands to the sea near Ogasawara, and although the area around Honshu is largely within an area of high pressure, the situation is such that moist air from behind the high pressure system tends to flow in.

As of 12:00, the temperature has risen in many places, with some places already experiencing summer weather, such as 25.4c in Osaka and 25.1c in Nagoya. Even in Betsukai Town, Hokkaido, where we observed a summer day and a winter day yesterday, the temperature reached 27.4 degrees Celsius. In many places, temperatures will rise further in the afternoon.



Except for Okinawa and Amami, most places are sunny, but in the afternoon, it will likely rain in Kyushu from the evening onwards from the west. In addition, strong cold air for this time of year will flow into the sky, making the atmosphere unstable, and it is likely that there will be showers in places in the afternoon. Furthermore, the probability of lightning occurring is high mainly in inland areas and along mountains in eastern and northern Japan. Please be careful of sudden thunderstorms and gusts of wind such as tornadoes. It will rain easily in Okinawa.




This situation is likely to continue into tomorrow. The probability of lightning occurring is high in the Kinki and Tohoku regions especially in the afternoon when temperatures rise, exceeding 80% in some areas. Please continue to be careful of sudden rain, thunderstorms, and gusts of wind such as tornadoes.

Temperatures are rising in various places; unstable atmospheric conditions will continue into tomorrow, 13th (Sunday)

2026/05/12 13:29

Today, the 12th, a rainy season front extends from the Nansei Islands to the sea near Ogasawara, and although the area around Honshu is largely within an area of high pressure, the situation is such that moist air from behind the high pressure system tends to flow in.

As of 12:00, the temperature has risen in many places, with some places already experiencing summer weather, such as 25.4c in Osaka and 25.1c in Nagoya. Even in Betsukai Town, Hokkaido, where we observed a summer day and a winter day yesterday, the temperature reached 27.4 degrees Celsius. In many places, temperatures will rise further in the afternoon.



Except for Okinawa and Amami, most places are sunny, but in the afternoon, it will likely rain in Kyushu from the evening onwards from the west. In addition, strong cold air for this time of year will flow into the sky, making the atmosphere unstable, and it is likely that there will be showers in places in the afternoon. Furthermore, the probability of lightning occurring is high mainly in inland areas and along mountains in eastern and northern Japan. Please be careful of sudden thunderstorms and gusts of wind such as tornadoes. It will rain easily in Okinawa.




This situation is likely to continue into tomorrow. The probability of lightning occurring is high in the Kinki and Tohoku regions especially in the afternoon when temperatures rise, exceeding 80% in some areas. Please continue to be careful of sudden rain, thunderstorms, and gusts of wind such as tornadoes.

Atmospheric instability will continue from this afternoon until tomorrow.Beware of showers inland and along the mountains in the Tokai and Tohoku regions.

2026/05/11 15:11

Today, the 11th (Monday), the rainy season front is stationary from the Nansei Islands to the Ogasawara Islands. The area around Honshu is widely covered by high pressure.
Active rain clouds are spreading near the Nansei Islands, and in Nakasuji, Tarama Village, Miyako District, Okinawa Prefecture, 37.5 mm of heavy rain was observed in the hour up to 10:39 a.m. Rainy conditions are expected to continue in the Nansei Islands into tonight.



Also, moist air is flowing into Honshu from the south behind the high pressure system, and strong cold air will flow into the upper atmosphere for this time of year.
As a result, the atmospheric condition will be unstable in the afternoon, so please be careful of showers and thunderstorms especially along the mountains and inland areas of Tokai and Tohoku.



The same pressure distribution will occur near Japan tomorrow, the 12th (Tuesday), and the atmosphere is likely to remain unstable.
Please be careful of sudden rain and thunderstorms mainly in the afternoon, mainly in eastern and northern inland Japan.



If you feel the following changes, it is a sign that a cumulonimbus cloud is approaching. Heavy rain and thunder will soon arrive. There is also a risk of strong wind gusts such as tornadoes.

+Pitch black clouds are approaching
+I can hear the sound of thunder
+A cold wind suddenly blows



If you notice any of these signs, be careful as the area directly under the tree is not suitable as an evacuation site due to the danger of side lightning strikes. Immediately evacuate to a safe place, such as a sturdy building or underground mall.

Weather for the week: High temperatures near Honshu, unstable and changeable weather; Okinawa is closed during the rainy season

2026/05/11 07:36

From now on, there will be many days when the area around Honshu will be covered by high pressure, and temperatures will be higher than average nationwide. The maximum daytime temperature will be around 25 degrees Celsius, and temperatures are likely to trend upward into the second half of the week.



On the weekend, there may be some places where the daytime maximum temperature is 30c. The predicted maximum temperature in Nagoya and Osaka on Sunday the 17th is 29 degrees Celsius, one step before midsummer day, in Kofu it is expected to be 31 degrees Celsius, and in Takayama City, Gifu Prefecture, it is expected to be 30 degrees Celsius.
Summer hasn't really started yet, but please be careful not to get heatstroke. It is best to take precautions such as hydrating frequently, taking appropriate breaks, and turning on the air conditioner indoors rather than holding back.

In addition to the rise in daytime temperatures, cold air frequently flows into the skies near Honshu, so there will be many days when the atmospheric conditions will be unstable, especially inland and along the mountains. From tomorrow, the 12th (Tuesday), there may be localized rain and thunderstorms in inland Honshu due to the influence of cold air in the upper atmosphere. Even if there is no umbrella symbol in the weather forecast, be careful of sudden rain or thunderstorms in the afternoon. Depending on the degree of development of rain clouds, severe phenomena such as lightning strikes and gusts of wind may occur, so it is necessary to pay attention to changes in the sky pattern.

The rainy season front will gradually move far south of Japan, so there will be many relatively sunny days in Okinawa and Amami. It looks like it will be a break during the precious rainy season.

Today's weather (Monday 11th): Clear skies around Honshu; watch out for sudden rain and thunderstorms inland and along the mountains in the afternoon

2026/05/11 07:08

Today, the 11th (Monday), the end of the week, the area around Honshu will continue to be within the area of high pressure. Meanwhile, the rainy season front remains stationary in the south of Japan.

It will be bright and sunny in many areas around Honshu. The maximum temperature during the day is expected to be around 25c in many places, so it will be a sunny day without the need for a jacket. In inland areas, the temperature difference between morning and afternoon tends to be large, so be sure to dress appropriately and stay in shape.



However, in the afternoon, atmospheric conditions will be unstable mainly in inland areas and along the mountains of eastern Japan due to the influence of cold air in the upper atmosphere. In inland areas such as southern Tohoku and northern Kanto, there is a high probability of lightning occurring, and thunderclouds are likely to develop and the weather may change suddenly. Even if there is no umbrella symbol in the weather forecast, be careful of sudden rain or thunderstorms.



Okinawa and the Ogasawara Islands will likely have a rainy day due to the influence of the rainy season front. There is a risk of localized heavy rain accompanied by thunder, so please be careful of flooding of low-lying areas, landslides, and rising river waters.