JACKSONVILLE, Fla. -

How many hours a day do you spend out in the summer sun? Although it's a good source of vitamin D and can help build your immune system, too much of a good thing can be dangerous.

Be sure to pick the right time to go outside. When possible, go out in the morning or evening. The sun's UV rays are strongest between 10 a.m. and 4 p.m., according to the EPA.

Always check the UV index before you head out. It's issued by the National Weather Service and provides a forecast of the expected risk of overexposure from the sun. A UV rating of 11 or more means extreme risk of overexposure.

Apply one ounce of sunscreen to all exposed skin 15 minutes before going outside. Your sunscreen should have an SPF of at least 30 and broad-spectrum protection from both UVA and UVB rays. Reapply every two hours, even on cloudy days, and after swimming or sweating.

It's very important for children to be protected from the sun.  Getting just one sunburn as a child more than doubles your chances of developing skin cancer later in life. A person's risk for melanoma also doubles if they've had five or more sunburns at any age.