Where I lived the temperature varied from minus 2C in February to plus 38C or so in August. It's hotter elsewhere (when we had 35C they had 42C north of Tokyo). And the hot period is very humid as well. 80+% relative humidity and 35C is hard. Drop to 60% and it's much easier. The humidity is a huge issue - unless you're airing the house every day you'll get mold and worse. I've seen mushrooms grow straight out of the wood inside homes.