Firstly, keep your cat hydrated—it is a good idea to have several dishes of clean, cool water available and easily accessible for your cat. If your cat is lazy and just wants to nap all day, wake them up every hour or two and bring a dish directly to them and encourage them to drink.
Keep your cat groomed: this is hairball season. As your cat sheds excessive fur in the summer heat, it is a good idea to use a de-shedding grooming tool daily.
Be aware of the signs of heatstroke in cats. Symptoms can include rapid panting, bright red tongue, red or pale gums, thick saliva, depression, weakness, dizziness, vomiting, and diarrhea.