Expectations for a shot of cold air overnight Wednesday led the National Weather Service to issue a frost advisory for eastern Suffolk County from midnight to 8 a.m. Thursday.

Look for chilly temperatures – upper 20s to low 30s – especially for areas to the east of the William Floyd Parkway, said Joe Pollina, weather service meteorologist based in Upton.

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The advisory means that sensitive plants could be damaged or killed if left outdoors or otherwise unprotected.

Thursday is expected to bring increasing clouds, highs near 60 degrees, with a chance of showers at night.

Overnight lows are expected in the lower 40s for Nassau and upper 30s to lower 40s for Suffolk, Pollina said.