The National Weather Service is warning of rain, heavy winds and the chance of hail Tuesday.
Some of the storms could produce heavy rainfall, between a half and three-quarters of an inch possible.
As of 12:30 a.m., the weather service said the worst of the rain and wind could occur Tuesday afternoon into the evening.
There is also a flash flood threat for the area, with torrential rainfall likely in any storms that develop.
The forecast has led to the cancellation of several events around Long Island, including the Northport Harbor Family Night which was scheduled for Tuesday night. The event has been postponed until Aug. 27, on Main Street, downtown Northport Village.
To check for power problems, see the PSEG-LI power outage map.