Korakuen Hall in the Summer?

Hi everyone,

Apologies if this has been covered. I did a search and didn't find anything. How is Korakuen Hall in the summer time? I'm heading to Japan for my second time in August and can book tickets either for Korakuen Hall or Ariake Arena.

While I'd like to go to Korakuen hall for the history, I'm dreading the heat again. We went to a sumo tournament last year and had to bow out about half-way through due to heat (different arena). Of course, that was going into the hottest part of the day. Thank you!