We have pretty hot and often humid summers, but because many of our foals have a lot of white markings (pink skin)I am reluctant to clip them entirely because of the sunburn issue. Most of our foals have very fine, horse like, haircoats and that pink skin will sunburn in a heartbeat.
So I comprimise. I head and neck, clip the underbelly and the lower legs up to knees. This allows them to dissapate heat fairly well without exposing all of that pink skin on the back and sides. For white faces, large spots on necks and white lower legs I clip WITH the hair to take off the really long shaggy stuff but leave enough for sun protection.
This kind of clip will also keep them warm enough if we have a sudden cool spell like this crazy spring!
Also I will use zinc oxide ointment (diaper rash ointment) on pink skined faces where they have rubbed off the hair while nursing.
When I occasionally have a very white one I've had to fully clip for one reason or another they then have to stay in the paddocks with a lot of shade instead of the pasture.
I worry about those long haired babies that just get soaking wet in the heat. Getting that hot just can't be good for them.
Charlotte