Uchimizu - the tradition where water is sprinkled over the roads is not only done to cool down the temperature but to also subdue dust from flying about.
Every year there is an uchimizu event held in Akihabara and this year's one took place last weekend. Usually there is a maid theme but this year it was all Yukata.
Following are photos from the event. All are HD 1920px x 1080px so you can use em as wallpaper too.