During the summer months your cat can get overheated! Since cats (and dogs) cannot sweat, heat exhaustion can cause illness and even brain damage. Make sure that your pet has a comfortable, cool place to stay during the day. Cats should be left indoors with the air-conditioning set on low. Give your pet plenty of fresh water. If you work, you can use a larger-than-usual water bowl and fill it with a lot of ice cubes. The cubes will melt, leaving kitty with cooler water throughout the day. Another good idea, especially if air conditioning is not an option, is to fill plastic bottles with water and put them in the freezer (do not fill to the top so that there is room for expansion when frozen). When they are frozen give them to kitty to play with. They will love playing with the cold water bottle, laying on it and rolling it.
There are so many people who think that cats love very hot weather and this is a misconception that can harm your cat(s).