SHERMAN, Texas (KXII) - Everyone knows to use sunscreen in the summer sun, but lathering up is just as important on cloudy days where dangerous UV rays can sneak in."We look at an overcast sky and we think we're safe," said Sherman Dermatologist Dr. Mark Koone.

"That's cloud protection or the clouds are going to provide protection. But no, they don't. Water vapor is not a very good sunscreen." Koon says more burns occur in overcast conditions because people mistakenly think the clouds block out the sun's most dangerous UV rays.

He says they actually can reflect onto the skin off of water, cement and even snow."All those things can be an issue," he stated.