Thanksgiving weather forecast: Temperatures to drop overnight, wind gusts up to 35 mph may impact parade balloons

Long Islanders heading into Manhattan Thursday for the Macy's Thanksgiving Parade, or doing anything else outdoors, are advised to bundle up, according to the National Weather Service.

The temperature Thursday is forecast to plummet from Wednesday's relatively balmy high of about 60 degrees to the mid-40s, with wind gusts that could hit 36 mph and lows just below freezing by the evening, when wind chill values could make it feel closer to the mid-teens.

The weather service said  the coming chill is courtesy of a disruption in the polar vortex above the North Pole, which is a pocket of spinning air that typically keeps cold winds from flowing south.

"Whenever you get jet stream dipping very far south, it allows a lot of air from the arctic to come sweeping in, and that cools everyone down significantly," said Bryan Ramsey, a meteorologist with the weather service.

Ramsey said balloons should be safe to operate in the parade, but handlers might need to keep them lower to the ground than usual.

"The stronger the winds are, the lower they have to fly them," he said. "That way they can keep the balloons under control."

Regulations in place since 1998 mandate the grounding of parade balloons if sustained winds of more than 23 mph — or, gusts of at least 34 mph — are present. 

On Friday and Saturday, daytime highs will peak in the low 40s with evening lows just below freezing.

"There will be plenty of sunshine, but the wind will certainly get you," Ramsey said of the weekend forecast. 

Sunday's high is forecast to reach 51 with a 30% chance of showers increasing to 50% after dark and an evening low of 36.