Do Pets Need Sunscreen?
Do pets need sunscreen? Yes, is the answer, under certain conditions. Obviously, your cat would normally need to be an outdoor/indoor cat. The weather is hot and your cat is light-coloured and/or has a thin coat. These are the cats with the highest risk.

Poor Bobby developed skin cancer from the sun
Even cats that don’t match the criteria mentioned can get suborn. The ends of ears, the bit between the ears and the eyes, and the nose are spots where the fur is thinner allowing harmful UV radiation to burn the skin.
The People’s Dispensary for Sick Animals (PSDSA — a long established and large UK charity) treated around 30 cases of skin cancer in 2015.
In the UK temperatures are rising and for the Brits 25°C (77°F) is hot so it is time to at least think about the possibility of your outdoor cat getting sunburn. PDSA pet hospitals mostly treated cats for sunburn in 2015:

Pet Suncreen
“Our statistics show we treat a number of pets each year suffering from these conditions. Light coloured pets and those with thin coats, such as whippets and cats with white ears and noses are at highest risk as they have less natural protection against UV radiation from the sun.”
The PDSA recommend Pet Sunscreen like the ones sold on Amazon. Cat owners should keep an eye open for ulcers and sores on their cat – the ears are the most susceptible – which indicates treatment is required.
Certain parts of the USA can become very hot. I’d have thought that despite the fact that many cat guardians keep their cats inside, some must be applying sunscreen to those sensitive areas around the head of their cat.