[sarasi]

Rainy season is late June to mid-July, it doesn't go into August. Other than the festivals (Gion matsuri in July and Daimonji yaki in August), I would avoid mid summer in Kyoto because the heat is brutal. It was 39 degrees C when I was there for the Gion matsuri twice. I personally am not a fan of sightseeing outdoors in very cold weather so mid-winter doesn't appeal to me much either. Autumn was nice there.

The most expensive and crowded times will be April because of the cherry blossoms, November when the autumn leaves have changed colour, the times of the major festivals, Golden Week, and Obon.

I also get bitten by mosquitoes if I forget the repellant but don't really see that as a reason to avoid a place. You will find mosquitoes all over Japan from late spring to autumn, so they are hard to avoid unless you want to come in winter.