Long Island weather: Cold overnight before a warm-up under mostly sunny skies

Monday night will be clear and cold, dipping to 29 degrees, before Tuesday ushers in the first day of winter with plenty of sun and a high about 45, forecasters said.

After a slight chance of rain on Wednesday and then another sunny spell, Friday and Saturday — Christmas, share the same 40% chance of rain, according to the National Weather Service.

There's a 20% chance of showers Wednesday, beginning after 1 a.m.

"This will be light precipitation nonetheless, with only a few tenths of liquid equivalent expected," the weather service said, predicting that the areas of north and west of New York City likely will see none.

After a clear and cold Wednesday night, with a low of just 28, look for a sunny but brisk Thursday, with a daytime high about 40.

Daytime on Christmas Eve should be warmer but possibly less sunny, with thermometers climbing to 46. Rain looks fairly likely that evening, forecasters said, with the temperature falling to about 36. Showers could continue Christmas Day, which will be cloudy and warmer with a high of 52.

That night, however, should be clear, cloudy and cool, with a nighttime low of 36.

Sunday should see the sun return, and it will be a warmish 47.