Conditions over the next 72 hours are expected to be mostly calm on Long Island waters, the National Weather Service said Thursday in its marine forecast.

But by Sunday -- Father's Day -- an incoming warm front and the remnants of tropical depression Bill could make it dicey for any boating activity, according to the service's Upton office.

Winds of 5 to 10 knots and wave heights of 2 to 3 feet or less are expected on most waters through Saturday evening.

See also7-day weather forecast for LI

High pressure moves east, off Long Island, Saturday night, and a warm front and the remnants of tropical depression Bill approach, the service said.

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"Southerly flow on the ocean waters could increase to 15 to 20 knots with 20- to 25-knot gusts," the service said. "Seas will build to 5 to 7 feet starting Sunday, and those rough seas could linger into the start of the new workweek."

Long Island's Thursday forecast calls for cloudy skies, a 30 to 40 percent chance for rain and daily highs in the low to mid 70s, the service said.