If the warm spring weather tempts you to jump in Lake Lanier — don't.
"You can't judge a book by its cover. The flowers may be blooming and it's 70 degrees, but the water is still very cold and that can be very, very dangerous," said Hall County Fire Marshal Scott Cagle, also a board member for Safe Kids, a coalition aimed at preventing accidental injuries.
Cagle said despite the warm weather Friday, the water temperature in Lake Lanier was just 56 degrees.
"That is way too cold to be doing any swimming," Cagle said. "You can die of hypothermia in 50-degree water within an hour."
Boating and other water activities can be especially dangerous for nonswimmers.
According to the Centers for Disease Control and Prevention, drowning is the second-leading cause of unintentional, injury-related death for children ages 1 to 14.
Natural bodies of water like Lake Lanier are deceptive because the depth of the water can change dramatically within a few steps of the shore.
According to the CDC, most drownings among those age 15 or older occur in natural water settings.
"Especially with all this rain we've had, everyone should know the lake is at full pool. Places you may have been able to touch the ground before you may not be able to," Cagle said.
The lake's first drowning of 2011 occurred last week when Roy Belrose, 66, of Buford was found in the lake by a neighbor.
Even for those who can swim, cold water is dangerous.
"When your body is 98.6 degrees at a normal temperature, you shock it with water that is 50 degrees," Cagle said. "Your body is not expecting that and you lose body heat faster in the water than you do on land."
Cagle said people who plan to be out on the lake fishing or boating need to follow all boating regulations and keep life jackets on board. He also recommended swimming and CPR classes.
"We just want people to prepared for the worst," Cagle said.
It takes water much longer than air to heat up, said Brian Lynn, a meteorologist with the National Weather Service.
It's typically the end of May before the water is warm enough for people to swim, he said.
"When the air temperature starts warming up, the lake water responds," Lynn said. "It takes a tremendous amount of heat to change the temperature of a volume of water. Lake Lanier is a sizable lake — is the biggest lake in the boundaries of Georgia — and it also has a significant depth. That all contributes to the amount of heat it takes to warm it up."
Lynn said swimmers may not have to wait too much longer to swim safely.
"If the trend continues with the warmer temperatures we've had in March, the lake will warm up quicker for sure," Lynn said.