An incoming cold front from the Great Lakes will push high pressure offshore starting Friday night and bringing the chance of rain to Long Island, the National Weather Service said.
While Thursday and Friday call for summerlike temperatures in the mid 80s with clear, sunny skies, the cold front provides a 50 to 60 percent chance of rain, the service's Upton office said.
Showers and thunderstorms are likely after noon Saturday and up to early Sunday morning.
By noon Sunday skies are expected to clear, with dry conditions returning and continuing into early next week. Slightly cooler temperatures, in the mid 70s, also are forecast.
Thursday morning drivers in Suffolk County were faced with "rapidly changing" visibility because of developing fog, the service said.
The Upton office had issued a special weather statement, effective until 9 a.m., warning of patchy, dense fog developing in parts of northwestern and southwestern Suffolk.
More fog could be part of the weekend forecast. Patchy, dense fog is likely to return Friday night and remain into Saturday morning as part of the incoming cold front, the service said.