Just buy long sleeved shirts that are a high SPF.

https://www.coolibar.com/kids-baby.html

A “regular” cotton shirt doesn’t provide much SPF. https://www.skincancer.org/prevention/sun-protection/clothing/get-in-on-the-trend

I’m a HUGE rash guard advocate but I do agree they’re hotter than normal shirts if you’re just playing in the sun. You may want to consider an SPF shirt if you’re trying to actually protect from the sun and don’t want to put sunscreen on their arms.

Don’t wear a rash guard out to play. They are hot! They’re only cool when they’re wet. Long sleeve exercise shirts are a different material and that’s what makes them cool. Rash guards are thick.

I think the swim shirts feel hotter than regular long sleeve shirts. The swim shirts have a lot of spandex in them, which doesn’t breathe well. Your workout shirts probably aren’t long sleeved.

OP here. Not for swimming, just being out in heavy sun. Thanks!

Do you mean to swim?

For swimming? It would be more comfortable, sure. A wet cotton shirt is heavy and clings.

For toddlers, I am wondering if wearing a long sleeve swim shirt (Jack and Cat polyester/spandex) would be more breathable and feel cooler than long sleeve cotton tee shirts. Thoughts/experiences? I know that my workout shirts feel cooler, but I’ve never worn a swim shirt. Thanks all!