Beach police are issuing warnings about dangerous riptides and high winds.
"The land will be leaving and the rocks will be rushing by. If you try to swim against it, you won't make any headway. It's stronger than even really good swimmers usually," said Peter Davis, chief of Galveston Island Beach Patrol.
Lifeguards have closed areas where they've seen rip-currents, but Davis has tips if you do come across one.
"You'll tire quickly. A lot of people will panic," he said. "If you're a good swimmer you can swim parallel to shore and swim out of it. If you're not a great swimmer or you're scared or whatever, if you just float and relax, it'll take you out past the end of the jetty and the waves will rock you back in where you can stand up again and you'll be fine."
On this busy beach weekend, you'll also find red flags posted on lifeguard stations warning swimmers of high winds and unpredictable currents.
"We recommend that good swimmers only get into their waist. Children and non-swimmers should stay completely out of the water," Davis said.
His last warning is one of common sense:
"A lot of times when people are on vacation, they just sort of throw caution to the wind and 'check their brain at the Causeway,' as we say here on the island," Davis said. "Just remember that we want you to have a good time, but you're responsible for your safety."
Beach patrol expects the red flag warning will be in place until at least Sunday afternoon.