Being out in the sun without protection can be very dangerous. Always protect exposed skin with suncream. Wearing a shirt will protect your body. A hat with a wide brim will help protect your head, face and neck.
On sunny days your body will need more water. Make sure that most of the water you drink does not have a lot of sugar in it. Softdrinks and other sugar drinks do not provide your body with as much water as water on its own.