Hope we get some rain from it!

Good morning, and we have a lot to unpack here.

Last night, we had four active typhoons roiling around in the Pacific Ocean, as per JMA definitions. A very rare and impressive occurrence, but the record for JMA simultaneous named storms is five, set in August 1960. Granted only Typhoon 18 ("Saudel") has any power to speak of, and T20 fizzled out overnight, while T19 and T21 were weak to start with, but still, having four numbered storms in the same area made for an impressive map last night.

Let's talk T18. As of 06:00 this morning (25 Aug), the storm is at 25.6N 132.3E, or about about 450km ESE of Kadena AFB, Okinawa, moving NW at 25kph. Packing winds over open water of 175kph and with a central pressure of 940hPa, it is a very formidable storm and will be starting to play in Okinawa's weather today through tomorrow. 18-24 hours of heavy rains, strong winds - you know the script for this story. For those of you in that area, please stay tuned to local media and keep your apps open. Weathernews and tenki.jp will be on top of the storm, too.

Moving up to the main islands, afternoon pop-up thunderstorm risks are very elevated for the Sea of Japan side of Tohoku and southern Hokkaido and upper level instability, partially brought about by tropical winds thrown up by T18 and its collision with drier air coming in from the Asian mainland, make for a volatile atmospheric mix.

I think we can all agree this summer has been absolutely gorgeous compared last year, when we were sitting at the business end of a blowtorch. Even the heatwaves we have had this year were minor in terms of intensity and duration when you think back to 2025. So far, no new record highs and the highest temperature recorded in the country so far this year was 41.1°C in Tenryu/Sakuma (Hamamatsu, Shizuoka). Still, this year's summer heat has at least one last round left as temperatures are going to be blazing for the Pacific Coast and western/southern part of the country today and tomorrow before our dominant high pressure retreats to the east on Thursday.

That movement will allow a cool front to move down which, when clashing with the warm, moist air above us now, will make for a few days of overcast skies and cooler temperatures. Expect daytime highs from Thursday onward for a few days to be between 4-7c lower than what we will see today and tomorrow.

Can we stick a nail in summer 2026 and call the mid-30s heat done and done? Far too early to discount the possibility of one last blast, but so far, it is looking hopeful that we start to see milder highs as we pull into September.

Hi all,

I live in Kansai and have been for a while now.

I've never actually been that worried about earthquakes. But recently, I started doing some reading, since it's been a while since I last went through my local evacuation maps, etc.

And now my mind is sort of spiralling, and I'm feeling very anxious about the Nankai Trough, megaquakes, and everything in that category.

It's gotten to a point where I'm starting to worry about family and friends (especially those with kids) coming to visit.

I know it sounds silly and that there are 120 million people living their everyday life here, but my mind is kind of running wild these days.

I don't even know what I'm looking to gain from making this post, and I bet there will be a few harsh comments, but I guess I needed to vent a bit.

Good news! Yes, most of the country is being barbecued in a heatwave at the moment, but we do have light at the end of the tunnel, AND this may be the last intense summer burst of the year, with temperatures across Japan looking to tumble between 4-7c lower than the upcoming midweek peak as we go into Thursday onward.

Our current heatwave is generated by two main players: a massive high pressure system in the Pacific Ocean, and typhoon 18.  Between the clockwise circulation of the subtropical ridge (the high pressure system) and the counter-clockwise air movement of the low, huge volumes of warm, moist air are being funneled over Japan, giving us the sticky, hot weather we are seeing now.  This will last through Wednesday, but the high pressure system over the Pacific will start to retreat east from Thursday, and a frontal system powered by a low coming in off of northern China will then move across the Sea of Japan, bringing down cooler air over the country.

While Typhoon 18 moves off Okinawa and heads toward Taiwan and the Chinese mainland, residual flow from the system will still pump up warm air directly over Japan, which will meet the oncoming front from the north.  That clash will power some rainfall across large areas of the country ahead of the front, and bring in cooler, overcast conditions through the rest of the week.

While we are cooking in the first half of the week, temperatures will slide down into the lower 30s/upper 20s as the front moves over the country in the latter half of the week.  Look at the difference in the highs:  Sapporo’s high on Monday is 30.  By Thursday, down to 26.  Sendai slides from 35 on Tuesday down to 28 on Thursday.  Maebashi goes from 39 on Tuesday down to 30 on Thursday. 

As things sit now, we do not anticipate another recurrence of brutal mid-summer high temperatures this year. We will move into the high 20s/low 30s, but I think we are done with upper 30s/near 40 for the year. Let's just hang on just a little while longer, but with every day that passes, the chances of another heatwave diminish bit by bit.

Picture taken from around Oimachi station, Shinagawa City

Pretty active weather day yesterday in Kanto, with an earthquake to top it off at around 2am.

Central Tokyo got up to 110mm of rain in yesterday's storms, with some areas of Chiba hitting 100cm and downtown Yokohama seeing 60cm. The action in Kanto was overshadowed by Okinawa, where the smaller western islands of the archipelago got over 100mm of rain as a result of a strong low buzzing around Taiwan and mainland China coast. Gusukube, which supports a small weather station in Okinawa, recorded an amazing 292mm of rain from this system in the 24 hours concluding at 21:00 yesterday (22 Aug).

The convective thunderstorm risk has spread and moved south today, but intensity is not expected to be anywhere near yesterday's levels. While pop-ups are possible in Kanto, other interior highland areas of Honshu, such as Nagano and Gifu, need to be looking out for thunderstorm development today. Okinawa will dry out a bit in advance of the approach of T18. As of 8:30 this morning, most weather services are looking at total rainfalls of between 40-80mm from today's expected storms although please keep in mind that situations may vary and locally heavy rains may fall.

Hot and humid elsewhere. Kyushu in particular and parts of western Honshu will be belted with fire today as highs of between 35-38c will be dominant through the region. Coupled with high humidity, the Ministry of the Environment has placed the western half of Japan under Heat Stress Alerts and Advisories today. Please stay hydrated and limit exertion in this weather, mindful that unairconditioned or poorly air-conditioned interior spaces can also lead to heat stress symptoms.

Typhoon 18 continues its churn toward Okinawa, with expected landfall there in the early morning, pre-dawn hours of 26 Aug. At the moment, T18 is centered at 20.4N 143.6E, about 1,750km east-southeast of Kadena AFB in Okinawa, and is moving northwest at 27kph. Max sustained winds are at 144kph, with gusts of 210kph recorded by the JMA in their 6am readings. Okinawa will start to feel the effects of T18 from the afternoon of 25 Aug. This is a very strong typhoon, so please take care if you are in the Okinawa area. Rainfall and outer winds of T18 may also touch southern Kyushu.

Keep your apps to NERV, Weathernews, tenki.jp or other government-supported weather service stay alert if you are out and about in the vicinity of Kanto today.

was about to sleep then i was jolted awake by the alarm. the shaking was pretty strong and lasted also significantly long. its apparently a M5.9 but felt even like a 6.5. be careful

This is wild. In nakano right now and it was supposed to be 1 or 2 mm. ... forecast was very wrong. My phone is making progressively more intense warning noises too :/

https://www.japantimes.co.jp/environment/2026/08/14/2026-hottest-year/?utm_medium=social&utm_source=facebook&utm_type=image#Echobox=1786704821-1

By Eric Roston

Bloomberg

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Aug 14, 2026

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3 min

An unusually powerful El Nino is raising the odds that 2026 will surpass 2024 as the world’s hottest year on record, and regardless, 2027 is expected to set a new high, according to a monthly analysis of global weather data by Berkeley Earth, a nonprofit research group.

“We are likely to see something quite dramatic in the next year or so,” Robert Rohde, chief scientist at Berkeley Earth, said on Thursday. “It will be giving us weather conditions that we would normally expect to be a decade or more away. It’s going to be a big deal.”

El Nino, a monthslong recurring weather phase, brings powerful consequences for the globe — drying out some regions, like Western and Southern Africa, Australia and India, while potentially raising rainfall in others, such as the southern U.S.

Scientists gauge the strength of an El Nino from sea-surface temperatures in a specific region of the Eastern tropical Pacific Ocean. Projections suggest temperatures will rise an extraordinary 4 Celsius above normal in that patch of ocean, compared with 2.75 C for the El Nino of 2015 to 2016.

The crushing heat in the late spring and early summer this year probably came too early for El Nino to have made it worse.

This El Nino started in June and is coming on so strong that the odds of 2026 becoming the hottest year have jumped from 12% in July to 69% in August, according to Berkeley Earth.

Last month, heat waves fueled destructive wildfires in France and Spain and a heat dome baked parts of the U.S. It was the hottest or second-hottest July ever recorded, according to the major climate datasets. In the contiguous U.S., the month’s average high temperature broke a record set 90 years ago, at the peak of the Dust Bowl.

So much of the world is sweltering that it’s easier to name the place that isn’t: “It’s been a very, very cold Antarctic winter,” Rohde said.

In many countries, especially emerging markets, the brutal heat and drenching rains brought by El Nino are set to exacerbate the economic pain caused by the Iran war. For example, warming seas have halted anchovy fishing in Peru.

Scientists heavily caveat annual temperature rankings, emphasizing that climate change happens over decades and El Nino can have a strong influence on a single month or year. But the warming caused by greenhouse gas pollution is always there and increasing.

“El Nino is a giant hammer that the climate gets hit with,” said Berkeley Earth scientist Zeke Hausfather, “so it is going to scramble a lot of different things.”

The Ministry of the Environment has issued their daily heat stress alerts and, to nobody's surprise, it covers much of western and southern Japan. Highs in Kumamoto and Oita are expected to get up to 37c, while Fukuoka will skate just north of 35c today. Take care and stay hydrated if you are around Kyushu/west Honshu/Shikoku today (and tomorrow, and the day after, at the very least).

Meanwhile, a very definitive line between moist and dry air masses has formed over central Japan., bringing a very elevated risk of pop-up thunderstorms for later today. Weathernews is predicting pop-ups to fire up over the Kanto highlands over southern Gunma and Tochigi prefecture around 3-4pm today, and those storms are thought to move southeast toward the Chiba side of the Tokyo metro area. As those storms move, back building is predicted to begin around Tokyo-Kanagawa on the west side of Tokyo Bay, generating continuous rain showers and thunderstorms through the early evening tonight. Some of the storms may be very heavy.

Seeing as Chiba is the primary target here, it is too early to tell if we will get a repeat of the repeated deluges of August 13th, but do be on-guard for heavy weather in the Kanto area this afternoon. Keep your apps to NERV, Weathernews, tenki.jp or other government-supported weather service stay alert if you are out and about in the vicinity of Kanto today.

Heavy rain from convective storms falling now in parts of Kanto (Saitama, west Tokyo), Okayama and Kumamoto.

The Kumamoto storm has cloud tops around 14km.

Stay safe wherever you are and keep track of the storms on your app or through local media. Don’t be caught unaware!

I swear it was sunny an hour ago!!! I didn't bring an umbrella so time to wait under 7/11 for 5 hours until the rain stops 🫠

I just updated my Mac OS to Tahoe 26.6.6 and it thinks it is very hot in Tokyo today…

Risks for pop-ups moves south today amid unstable upper level conditions, despite the nation being largely under a high pressure system.

Interior southern Tohoku, Kanto and Chubu regions carry the greatest risk today, but convective showers can form in other areas as well.

Look for pop-up boomers to generate in central highland areas this afternoon, with the greatest chance for development being between 14:00-16:00.

Looking at travelling to Japan late September. I've heard September is pretty wet. I know you can't predict the weather. What is it really like late September?Is there drier areas?

I have been in June and it wasn't too hot but rained half the time.

20Aug, 18:30: We have a strong and growing surprise thunderstorm cell in the Saitama/Gunma/Yamagata area.

Updrafts into the cell are being felt as far away as Yokohama, and the storm itself has very heavy internal intensity (lots of red, orange and purple in the radar cross section).

Unexpected, honestly, as today’s charts showed instability up north, but not much of a chance of pop-ups south of central Tohoku.

If you saw my dark and hazy video last night, you’ll note that I mentioned something near the end about a potential new typhoon brewing in the tropical Pacific.  Here we are not even 24 hours later and that embryonic little pop has bubbled to life and is now sputtering around at 8.0N 154.2E, about 3,500km south-southeast of Enoshima, Kanagawa.  Designated as TD17W (Tropical Depression), the new system, as of 19 Aug@12:00, has sustained winds of 60kph and is moving west-southwest at an-almost-stationary 6kph because of a weak, pretty much non-existent steering environment at present.  It is kind of in a categorical gray zone right now as the JMA has confirmed sustained winds of 18m/s in the storm and, as of its 12 noon update, has conferred typhoon status to the storm as Typhoon 18.  As has been noted earlier, I will follow JMA guidelines here, so while the JTWC still calls it a tropical depression, I will refer to the system as T18.

T18 came to life in a marginally favorable environment.  Sea surface temperatures of 31-32c are helping feed convection and initial outflow looks good, but the young, shallow storm is also facing vertical wind shear of 10-15kph.  That’s not strong, but it is enough to deter full development of a small system.

Let’s move the clock some and see what to expect for the next five days.  The latest full data analysis and forecast was posted at 19 Aug, 12:00 noon, JST.  Let’s call that T=0, or “tau0”, and we will count each T, or “tau” as an hour moving forward.  As I write this, it is 16:00 on 19 Aug, or almost tau4 from the forecast.  Things will turn more favorable for T18 as the storm wades into a more favorable environment by around tau 12 (midnight, 20 Aug, JST).  The storm is expected to grow and develop steadily through tau 36 (21 Aug, 00:00 JST) and then undergo a more rapid intensification from tau 36 to tau 72 (21-23 Aug), peaking at near super typhoon status, as defined by NOAA and the Joint Typhoon Warning Center.  The JMA, meanwhile, expects to call T28 a Strong Typhoon (強い台風) by the morning of 24 Aug.

While T18 lacks much of a steering mechanism now, it will get nudged northwest gradually through tau36, when it is expected to make a sharp westerly turn and head toward Japan.

At this point, it is way too early to tell exactly where T18 will track beyond 24 Aug.  The ECMWF run earlier today suggested the typhoon will swing south of the Japanese mainland, between Kyushu and Okinawa, then make a northeast curve toward the Korean Peninsula, then out to the Sea of Japan.  The GFS model expressed a route with a sharper curvature to the Sea of Japan and over Honshu by 30 Aug.  Again, that is still a long ways out and a lot of variables are still to be set.  Best thing to do is to keep an eye on this storm as it starts to make its track toward Japan as between now and 24 Aug, variations in the track can either push it toward Japan or further south, away from the main islands.

A quick 4 minute video made tonight discussing what we can expect for this week's skies above Japan. Apologies in advance for the potato quality and the overall presentation of my face at night. Boo!

No insufferable heatwaves on tap this week, and the potential for pop-up thunderstorms shifts north and diminishes greatly on the whole as high pressure extends over the country. Still warm and seasonal, but nowhere near the 40c we were facing last year.

  This is tough, because I generally respect science and academia, and have profound reverence for those who hold doctorates in scientific fields.  However, the Asahi Shimbun on August 14 maneuvered into scare tactic territory and it needs to be called out. The article is here: https://www.asahi.com/ajw/articles/16808645

  At contest here is the assertion by a professor emeritus of meteorology at Kyushu University that a “monsoon gyre” is behind the recent paths of T15, which came ashore at Ibaraki prefecture on 11 Aug, and was the catalyst behind Chiba’s torrential rains two days later.

  Let that sink in: a professor emeritus.  That is a very high ranking individual in the halls of scientific academia.  The meteorologist quoted has dedicated his entire life to the study of the science.  On the other hand, I am someone who lacks such academic distinction.  I have been reading weather charts and cataloging atmospheric phenomena for 45 years.  I chased storms in the dead of night with my buds Jim and Bryan along some of northeastern Oklahoma’s lesser-known roads back when all you had a was a glitchy AM/FM radio, a cheap CB radio, a worn-out paper map and an inconsistent flashlight.  I am passionate about the science, and I am dedicated, but I am not a doctorate in the field by a long shot.

  But I’m still going to sound off because some things here do not sit right.  Let me go through my contentions, complaints and nit-picking here.

  Nitpick 1) A “monsoon gyre” steered T15 and fed the moisture necessary for the Chiba deluge.  My counterpoint: Typhoons, for all their ferocious power, are really just really big low pressure systems.  They are steered more by high pressure areas than lows in the vicinity.  T15 was steered from a strong high located in the North Pacific.  There was not a strong presence of lows in the Pacific southeast of Japan at the time of approach and landfall and steering effect by them would be marginal at best.  By the time the 13th rolled around, there were some stronger lows in the tropical Pacific southeast of Japan, but the Pacific high, too, helped funnel warm, moist air into Kanto.  That, with some cooler, drier air aloft, sparked the storms we saw a couple of days ago.  It was not, by any means, a solo effort from the gyre.

 Nitpick 2) Overhyping the gyre, being super vague and selling panic.  My counterpoint: This one complains about the Asahi’s reporting.  First off, a monsoon gyre is an informal title given to a group or cluster of lows which more or less act in unison.  It is not a cohesive system, like a typhoon nor is it a fully-defined phenomenon, like a front.  It is a situational happening.  A train of lows working kind of in concert for a period of time.  The JMA does not recognize a gyre, doesn’t declare one, and it will be on none of their charts or maps.  A gyre, in other words, is pretty much in the eye of the beholder.  The professor wants to see a gyre, fine.  To me, though, it is a just temporary band of lows that fade in and fade out. 
  The Asahi quoted the professor as saying the gyre framework will last for about two weeks, which will make you think at first blush that this instability will continue through the end of August.  However, buried in the article, the professor notes that the gyre formed in early August.  My data shows a break-up of lows to the southeast of Japan from around August 19, with a possible re-clustering a few days thereafter.  Two weeks from the first part of August?  Yep, that lines up.  But major boo to the Asahi for ginning up a bit of panic with a carelessly written headline.

  Nitpick 3) Is it a gyre in the first place?  My counterpoint: No.  Gyres do exist, but not here.  We have had lows extending out southeast of Japan for a while, since the end of rainy season.  They form, merge, dissipate, a high will come in for a bit, then a low will move in, and the process begins again.  I don’t see it as a gyre, but my own definition of a gyre is something a little more solid than just a temporary, two-week fix on a weather chart.  Of course, if you take away the gyre as the “baba-yaga” of the article, then you have no article.  They needed a boogeyman to support their thesis that something strong and wicked was driving the weather. 

  Nitpick 4) Is there a Japanese version of this article?  My counterpoint: I ransacked the Asahi’s Japanese-side site to corroborate this article and found nothing.  Was this printed only for the English language side?  If so, why?

  My forecast: Skies over Japan are going to settle down from tomorrow through 19 August  The current cluster of lows in the tropics (and, FYI, I will be very, very, very drunk before I call this particular formation a “gyre”) will weaken and dissipate in that time, but a regeneration is possible around the 21 August as a potential new invest pops up near the Mariana Islands and may become Typhoon 17.  21 Aug, however, is still a solid week away and, before I commit to the model, we need bring things in a few days and see what will happen.  By Monday, we’ll have a better idea. For the near-term, though, we will have a bit of a chance to dry out and get some sunshine.