Long Island weather: Temperatures to fall to the 30s, middle 20s as cold weather arrives, forecasters say

Don your coats! After an unseasonably warm fall, temperatures have fallen and will continue to be low this weekend and into next week on Long Island.

The National Weather Service's Saturday forecast for Islip predicts a high near 41 during the day Saturday and 25 overnight, with wind chill values between 25 and 35 during the day and between 20 and 25 at night due to westerly winds that could gust up to 25 mph.

"People are used to it being pretty warm for the last couple of months. So this several-day period of cold weather will shock people back into the fact that it's winter," said Matt Wunsch, a meteorologist with the NWS in Upton.

Sunday's forecast high in Islip is around 39, falling as low as 24 at night, and temperatures are likely to remain low throughout the week.

After an unseasonably warm fall, this week's weather is unseasonably cold: Islip's forecast is eight degrees below average today and nine degrees below average tonight — compared to past years.

There is little chance of snow or other precipitation over the weekend into Monday and Tuesday, according to Wunsch.

Wunsch said the colder weather is due to western winds coming in from Canada.

"We had that system a couple days ago that brought some rain for the area. Behind that ... low pressure system that moved out, we're getting these west and northwest winds that  are bringing down this colder air from Canada," he said.

The falling temperatures on Long Island come as Western New York prepares for up to 4-6 feet of snow, with snowfall rates of 2 to 4 inches (5 to 10 centimeters) per hour. Lake-effect snow happens as warm moist air from the Great Lakes — which are unseasonably warm at the moment — rises and mixes with cold dry air overhead.

In a prepared statement, Gov. Kathy Hochul's office said the weather in parts of western New York could create "hazardous to impossible travel conditions" over the weekend.
Beginning Friday, the New York Department of Transportation imposed an empty and tandem commercial vehicle ban on I-86 from the Pennsylvania state line to I-390 and on State Route 219 from the Pennsylvania state line to I-90.

Gov. Kathy Hochul has declared a disaster emergency for targeted counties, which allows state agencies to mobilize resources. 

"Alongside our partners in local government, we are taking every step necessary to protect New Yorkers and keep our communities safe," Hochul said.

As of Saturday morning at 8 a.m., the New York State Thruway banned all commercial vehicles in both directions from Exit 46 (Rochester — Corning — I-390) to the Pennsylvania line until further notice. The most western part of the New York Thruway is closed to all westbound traffic west of Exit 57, which is just south of Buffalo.