Wet weather overnight Wednesday will give way to clear skies for a Christmas Day when temperatures are expected to be unseasonably warm as they climb into the mid-50s, forecasters said.
"The normal high temperature for December 25 is 40 degrees," said John Murray, a meteorologist with the National Weather Service in Upton.
Murray said rain will taper off by 10 a.m. Thursday, the clouds vanishing and letting sun through by early afternoon. The day will have some strong gusts, though, reaching up to 35 mph.
There is a low chance for isolated damaging wind gusts as a strong frontal system arrives early Christmas morning, the weather service said.
Between 1 a.m. Wednesday to 1 p.m. Christmas Day, forecasters expect slightly more than 1 3/4 inches of rain to accumulate for most of Nassau and Suffolk counties.
Dense fog on Long Island will cut visibility to a quarter-mile or less until about 6 a.m. Thursday, the service said in an advisory issued just after 4:30 p.m. Motorists should slow down and put more distance between vehicles because visibility was "rapidly dropping" due to mild air flowing inland off the ocean, meteorologists warned.
Showers drenched last-minute shoppers and commuters Wednesday afternoon and evening. Police reported several accidents but no serious injuries. At one point, two lanes of the eastbound Long Island Expressway in Syosset were closed at Exit 43, South Oyster Bay Road, due to flooding, state transportation officials said.
The wet weather already was causing delays of 15 minutes or less Wednesday afternoon at Long Island MacArthur, LaGuardia and Kennedy airports, according to the Federal Aviation Administration website, www.fly.faa.gov.
Conditions may cause flight delays across the Midwest and Northeast, forecasters said.
The FAA advises travelers to check with their airlines for possible delays.
Murray said Friday also will be mild, clear and dry, with temperatures reaching the upper 40s and low 50s, leading to a Saturday with similar conditions.
With Ellen Yan, Candice Ferrette and Gary Dymski