However you should at all costs try to avoid over exposing your natural hair to the sun in order to maintain healthy hair. Heat damaged hair is much more suceptible to sun damage as is color treated hair. Unprotected hair may be suceptible to breakage due to the harsh UV rays.
For that reason, I highly suggest using a good leave in conditioner that contains a sunscreen to lock in the moisture and help nourish dry hair.
Other important things for protecting your hair in the summer sun are to try to avoid using excessive heat methods such as the blow dryer, curling irons and glat irons. Protect your hair by wearing hats or scarfs and by using protective styling!