Yes, the Typhoon Lagoon water is heated. (I work there) Our wave pool, Lazy River and slide water temps are about 78-82 degrees right now and the kiddie area is around 83-84 degrees. The only water that you might deem cool is the water in the Shark Reef which is about 68-72 degrees-it's salt water and kept cooler for the fish that live there.
Hope you enjoy your visit! We're looking forward to a great weather week!