You are correct that exposure to strong sunshine can cause skin problems in pets. In cats, the problems most frequently occur on the tips of the ears, on the nose, or around the eyes. The affected areas develop scabs or sores, which may or may not be itchy or painful. In some cases, the sores can be precursors to certain types of skin cancer, so they need to be taken seriously.
However, it is by no means certain that the sun is responsible for your cat’s problems. Skin problems anywhere on the body can be caused by allergies. During the summer, allergies to a wide variety of insects and plants can cause the sort of problems you describe.
First and foremost, Oklahoma is flea country. Fleas are much more common in warm weather, and they could be causing, or at least contributing to, your cat’s problems. Remember that your pet does not need to have a visible flea infestation to have flea-related skin problems. In sensitive individuals, an isolated flea bite now and then can trigger major issues. Keeping fleas out of the picture is a must.
As well, a large number of plants that bloom during the summer could be playing a role in this matter. Believe it or not, mosquito bites might be involved as well. These types of allergies may be treatable with antihistamines or, in severe cases, cortisone. For the record, you should not apply insect repellents to your cat.
Here are my recommendations. Try to keep your cat indoors during peak sun hours, which typically occur from 10:00 am to 3:00 pm. Apply Advantage or Frontline every 3 – 4 weeks. If the sores still develop, I recommend that you have your vet perform a biopsy. This is a relatively simple procedure (although a brief period of anesthesia will be required), and it will likely yield a great deal of information about how to prevent or treat this syndrome. As well, it should tell you whether your pet is at risk for more serious problems, such as skin cancer.