A flood advisory has been issued until 8:15 p.m. for Nassau County, the National Weather Service said Monday evening.

Heavy rainfall was moving across Long Island, and an additional half-inch to an inch of precipitation was still expected in some areas. Weather officials warned about flooded highways, streets, overpasses and low-lying areas.

The Long Island Rail Road advised customers to expect delays in and out of Long Beach due to switch trouble near the station. Both Kennedy and LaGuardia airports were experiencing inbound flight delays averaging more than two hours because of wind.

The NWS said a coastal flood warning had expanded to Monday night for Long Island's Twin Forks, including in the Town of Riverhead. There also was a coastal flood advisory issued for the New York/New Jersey harbor, Jamaica Bay and Great South Bay on Monday night. A coastal flood advisory was set for Jamaica Bay and Great South Bay on Tuesday.

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About an inch of rain is forecast for Long Island, with the potential to be higher locally.

With leaves still on some roads and the ground saturated by Saturday’s rain, runoff could lead to some minor flooding, maybe “a lane closed here or there,” said Nelson Vaz, NWS meterologist.

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Minor to locally moderate coastal flooding is expected for vulnerable areas around high tide times Monday overnight, the weather service said.

Eastern Suffolk can expect winds of 20 to 30 mph, gusting to 50 mph, according to a wind advisory issued for 6 p.m. Monday to 1 a.m. Tuesday.

Looking ahead, “Most of the week will be dry and temperatures will remain below normal,” News 12 Long Island meteorologist Rich Hoffman said.

Both Tuesday and Wednesday are expected to be breezy and dry, with some sun and clouds, and highs in the lower 40s.