Though it will be warm and sunny all week, a dip in Lake Lanier may not be as pleasant as it seems.

It is expected to be sunny this week with high temperatures climbing to the low 80s by Thursday, said Jessica Fieux, a forecaster for the National Weather Service.

But the hot temperatures can be deceiving. “That should help to warm the water temperature up; however, the water won’t respond as quickly as the air will,” Fieux said.

Cold water is not only uncomfortable but dangerous.

Last week, emergency personnel responded to a report of a possible drowning at Tidwell Park in eastern Forsyth County.

Forsyth County Fire Capt. Jason Shivers said a 36-year-old man had fallen off a personal watercraft and was unable to get back on. He was hanging onto the side of the machine and could not be seen from shore.

Shivers said the man, whose identity has not been released, was wearing a life vest. The sheriff’s marine patrol unit brought him safely to shore.

Hall County Fire Chief David Kimbrell said in the spring, incidents on the lake are rare, but do happen.

“Typically it’s just somebody falling out and getting in the water accidentally,” Kimbrell said. “Nobody really goes swimming this time of year.”

Even when it’s warm outside, cold water can cause hyperthermia and make it difficult to swim to safety.

“Typically your body is 98 degrees and the water temperature right now down deep is probably 50 or 60 degrees,” Kimbrell said. “That doesn’t seem like a lot, but water takes heat away from your body a lot faster than air. You’ll cool off a lot quicker.”

“People think the water temp warms up as fast as the air temp but it doesn’t,” Kimbrell said.

Kimbrell said even in the summer time, deep areas the water can be very cool.

“People jumping or diving hit that cold water,” Kimbrell said. “People need to use their own judgment. It’s better to wade in and not just dive in.”

Times regional staff writer Julie Arrington contributed to this report.