Tokyo weather warning 18 September
 

We will fly IMT - HND tomorrow on ANA departure at around 18.00 and got a weather warning, our son will fly an hour earlier on JAL to Sendai and did not receive any warnings about cancellation or flight diversion.

How likely/serious are those weather disruptions according to regular flyers out of HND?

We will leave for Europe on the 19th, but on separate tickets that is why we leave a day early.

What weather warning? The JMA has nothing on its site, and the weather report looks pretty standard. Hot, some rain, and then getting (finally?) cooler.

Ota-Ku has both heavy rain and heatstroke warnings on JMA https://www.jma.go.jp/bosai/#lang=en...a_code=1311100

FWIW Apple Weather says about 1.05" of rain for the day (between Light and Moderate), starting at about 6 pm. It looks to end by 6 am on 19th.

Guessing IMT is actually ITM?

Thanks to Freecia and Pickles.
This is the warning I found in my mail and which is still on the ANA website: Thank you for flying with ANA.
Please be advised on the status of flight operations impacted by thunderclouds, and also the procedure for change (transfer) and refund for passengers who request to do so.

Flight NH0036 ( Osaka(Itami) - Tokyo(Haneda) ) on 18-Sep may be delayed, cancelled, landed at another airport, or turned back to the point of departure due to airway congestion or ground work stoppages caused by approaching thunderclouds.
The situation may change depending on the path and speed of thunderclouds in the future.

Cooler weather is certainly welcome. On this trip we walked 8km a day (including quite some temple and castle steps) and it was not always easy going.

Update: delay of 10 minutes because of late incoming plane. Weather check notice near the gate, but smooth flight and dry weather at arrival.

The bad weather was initially expected to come mid-afternoon but came late at night instead.

The south side of Tokyo was absolutely inundated last Thursday afternoon, with half of the Tokyu lines out of service for several hours because stations south of Meguro and Gotanda had completely flooded. A lot of buildings in low-lying areas like Jiyugaoka were also flooded. HND was also temporarily shut down and a lightning strike was powerful enough to tear the asphalt in one of the runways. I think they were expecting a similar situation yesterday and decided to warn people in advance.

We found out the hard way. Had booked a hotel near Haneda as to have an easy connection the next day. Hotel restaurant closed, so we ventured out with two umbrellas but were washed of the street. Returned after a few hundred meters and ended with an empty stomach. :-(

Glad it still worked out for you especially with the luck of booking a hotel near Haneda.

I've seen some Sept 11 2025 videos of people driving through flooded areas and others walking barefoot down flooded metro stations & streets. Some people got stuck in a basement restaurant which was flooding down the stairs so empty stomach due to being driven back by the weather almost fortunate to bypass that type of "adventure". Sometimes you can find a vending machine with instant noodles or beer snacks in the hotel or buy a snack from airport convenience store on arrival, before you go to your hotel especially if isn't connected to the airport.

I usually pick up some shelf stable snacks and water & pre-charge devices if there is a typhoon warning while I'm traveling in Japan. A bit cautious but it can take a while for things to resume. As long as you're safe, dry, and fed, it's just easier to take it all in stride.