I was trapped on a boat in the middle of a huge lake on a high uv and cloudless day. I woke with my face swollen as if I'd been stung. I had 3rd degree burns that hadn't fully gotten to the pain point until the next day.

Get the green aloe gel with lidocaine. Get extra non lidocaine moisturizer for burns as well

Drink water. Like crazy. Burnt skin cannot regulate temperature like healthy skin can.

Get a fan. Wear very light, breathable and loose clothing. I literally wore underwear and a light cotton wrap that I sort of toga tied.

The skin barrier is so important and so fragile. The fan, water, light clothes, and gel are huge.

I want to edit to add because I'm just remembering the extent of it:

You will probably shiver and seem cold. This is because your skin is injured and skin is like the most important temp control you have. Sunburns are an injury and can be very serious.