Upsides: AC everywhere and you rarely have to go outside except between cars and buildings!
Downsides: MUCH hotter than Japan, humidity is worst at night, and it doesn’t really cool down (still in 90s!). The humidity may not be as bad, but because of a lack of breeze, it feels stickier than in Japan. There are days that are less hot but they’re still all HOT from June-August and mostly hot in May and September.
Upsides: Much less hot, and the evenings are nice (low humidity + cool), so you can still go out sometimes, there is a BREEZE. Humidity feels more wet than sticky. There are “off days” where the weather is nice. Summer is shorter than in Dubai!
Downsides: The Japanese use air conditioning and most places DO have it, but they skimp on it. Because it’s a much more pedestrian/public transport place, the heat is unavoidable unless you drive. BUGS. Typhoons (occasionally, and typhoon season goes beyond summer anyway).
I prefer summer in Japan to summer in Dubai (and I say that having been pregnant in the summer in Japan and being in the country all summer, neither of which were ever the case in Dubai), because the evenings and early mornings are nice enough to go out and enjoy being outside. But that said, I definitely prefer hot weather to cold weather and humidity to dry weather, as long as I’m prepared to sweat (that’s the only way to cope… just expect to sweat!).
It’s also been interesting to see how they handle the heat here – yes, people go out less, but they are also prepared with paper fans (that are surprisingly effective!), hydration, umbrellas as parasols, wash cloths to wipe sweat away, and some women will wear long gloves to protect their skin from the sun (I haven’t tried them; they seem like they would be WAY too hot!).
But even so… I’m glad the weather is cooling off. 😉