It may feel like summer, but the Coast Guard and New Hampshire’s Marine Patrol are warning boaters that the water in the Northeast is dangerously cold.

“I wish I could say it in gentler terms but, plain and simple, cold water shocks, incapacitates and kills,” said Al Johnson, a recreational boating specialist with the Coast Guard.

At least three people have died in near-freezing waters in the Northeast this spring, including a canoeist in Mattituck on Long Island, N.Y., a kayaker in Jamaica, Vt., and a man who tried to save a youngster who was struggling in 38-degree water in Lancaster, N.H.

The Coast Guard issued a cold water safety advisory Wednesday for anyone hoping to take advantage of the warm weather by doing some boating. Johnson says water temperatures in lakes and ponds remain close the freezing point and are not even remotely tolerable.

David Barrett, head of New Hampshire’s Safety Services Division, says low water temperatures are a special hazard for small craft such as kayaks and canoes.

“Anyone who capsizes or falls overboard can only survive for a few minutes because of the stress that cold water places on the body,” Barrett said. “It rapidly saps the strength of even a strong swimmer.”

Barrett said water temperatures of 60 degrees or below are considered cold and temperatures currently are around 40 degrees in most New Hampshire waterways.

“The shock is so immediately incapacitating once you hit that cold water,” Johnson said.

Both agencies said the spring snow melt also has flooded many rivers and streams, creating even more hazards.

Safety tips for early season boaters include wearing life jackets and insisting that passengers or paddling partners wear them as well.

Other tips: paddle in pairs, check weather conditions and forecasts, ensure that someone else knows your boating plans and if you capsize, stay with the boat.

AP-ES-04-23-08 1400EDT