Long Island weather: Cold Thursday, then frigid through Saturday 

After a relatively mild January, February's first week is featuring a dive in the mercury, including a couple of days of dangerous cold, forecasters said

Thursday, like Wednesday, will have a high in the mid 30s and a nighttime low in the 20s. But winds will begin kicking up Thursday night, making it feel like it's between 15 and 20 degrees, even though a low of 27 is forecast.

That will set the stage overnight for a "dangerously cold air mass" arriving Friday. It will be sunny but temperatures will fall to about 19 degrees by 5 p.m. with steady winds of anywhere from 24 mph to 38 mph and a nighttime low of about 6, the National Weather Service predicted.

"Wind chill values during this time may fall to as low as 10 to 20 below zero for coastal locations," the weather service said, with temperatures Friday night and Saturday about 15-20 degrees below normal. Saturday will remain blustery and the high will be in the mid 20s, with a low of 19 at night.

Roads may be slick Saturday night as warmer air comes in, and temperatures should rebound Sunday to the mid-40s. By Tuesday, highs could reach 50 degrees, the weather service said.