Getting on your bike isn't just about looking cool, contrary to common opinion. Shorts, a T-shirt, and sandals are not appropriate riding wear, no matter how hot it is outside. When you slide, even jeans have just a sliver of protection against injuries and road rash. Leathers or reinforced coats, trousers, and boots may provide extra protection.
If you have an open-faced hat, you must wear glasses or goggles, and gloves can still be worn to cover your hands. In hot weather, there is special equipment installed for ventilation and cooling. It should also go without saying that you should still wear a DOT-approved helmet while riding. A Good best motorcycle helmet is another thing that must be there while riding a motorcycle.