Alan Brothers, 26, was pulled from the waters of Bellport Bay at 2:25 a.m. -- more than an hour after he went into the water. Police said a crew from South Country Ambulance took Brothers to Brookhaven Memorial Hospital Medical Center suffering from hypothermia.
According to the National Buoy Data Center, the water temperature for South Shore waters off Islip are currently about 61 degrees. The temperature may be slightly warmer in shallower waters closer to shore, especially in bay areas, but are still in the low 60s.
Meteorologists said water temperatures are actually about 5 degrees warmer than usual for this time of year.
Police said the missing swimmer was reported in a 911 call placed by Brothers' girlfriend at 1:35 a.m.
She told police Brothers had gone for a swim at Shirley Beach Park on Grandview Drive and Parkview Drive in Shirley, but never returned.
Police said Seventh Precinct officers responded to the scene, requesting the assistance of both the Marine Bureau and the Aviation Unit.
Marine Bureau Officers John Mullins and Don Moore used radar and thermal-imaging cameras to locate Brothers in the darkened waters -- about 175 feet from shore, police said.
No charges were filed. It was not clear what prompted Brothers to go for a swim.