The Nassau County department of health is advising beachgoers at 14 North Shore beaches against bathing and swimming because of elevated bacteria levels following heavy rainfall.

The bathing ban is in effect until 8 a.m. Monday, according to health department spokeswoman Mary Ellen Laurain. But it could be lifted or extended based on Sunday night’s weather, which National Weather Service meteorologists in Upton predicted would have a less than 25 percent chance of passing showers or thunderstorms.

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Storm water runoff because of heavy rainfall can elevate bacteria to levels that are higher than state standards, the health department said in a news release.

The affected beaches are: Centre Island Sound, Ransom Beach, Soundside Beach and Stehli Beach in Bayville; Creek Club and Lattingtown Beach in Lattingtown; Laurel Hollow Beach in Laurel Hollow; North Hempstead Beach Park in Port Washington; Piping Rock Beach Club in Locust Valley; Morgan Sound and Pryibil Beach in Glen Cove; Theodore Roosevelt Beach in Oyster Bay; Sea Cliff Village Beach in Sea Cliff; and Tappen Beach in Glenwood Landing.