With a strong southerly flow and rough conditions expected through Tuesday, a small craft advisory is in effect for Long Island waters, the National Weather Service said in its marine forecast.

The service's Upton office said Monday that the advisory runs from 10 a.m. Monday to Tuesday evening for the South Shore waters, from Montauk Point west to Sandy Hook, New Jersey.

The advisory ends Monday night for Long Island Sound, New Hark Harbor, Peconic and Gardiners bays and South Shore bays from Jones Inlet through Shinnecock Bay, the service said.

The advisory means that sustained wind speeds or frequent gusts of 25 to 33 knots and sea heights of 5 feet or higher are expected. The conditions also mean that small craft mariners, especially those operating smaller vessels, should avoid navigating in these conditions.

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Beachgoers Monday also should be aware of a high risk for rip currents at South Shore beaches, the service said.

Inland conditions across Nassau and Suffolk counties Monday call for partly cloudy skies, humid air and temperatures in the mid 70s. South winds are expected to be breezy, with some afternoon gusts more than 20 mph.