Mother Nature is taking that “Let It Snow” thing a little too seriously.

New York’s first significant winter storm of the season will make Sunday travel a mess — and could to dump 1-4 inches of snow on the city and on Long Island before it passes, forecasters warned.

The first part of the storm will arrive midday Sunday from the south, according to Accuweather. About an inch of snow could collect on the ground in the five boroughs and on Long Island.

“This if a very difficult storm to prepare for,” Sanitation Commissioner Kathryn Garcia said Saturday. “We have cold air in the beginning. We have a period of moisture and rain. And then we have cold air on the back end.”

The city’s fleet of 705 salt spreaders are loaded and ready to go, Garcia said — and 1,500 plows will be deployed once two inches of the white stuff accumulates.

“There might be a small accumulation before it changes over to mostly rain later Sunday,” said Accuweather meteorologist Tom Kines.

Areas north and west of the city will be colder, and may see freezing rain or some light accumulation of snow.

The Hudson Valley is expected to see 6-12 inches of snow, and up to a foot could fall in northern New Jersey, the Catskills and northeastern Pennsylvania.

Southern Connecticut, Rhode Island and much of Massachusetts are under a winter storm watch, with up to a foot forecast in those regions for Monday as well.

But if the front shifts just slightly, the city could see more snow, Kines said.

“There’s not a whole lot of margin for error on this one,” he added.

Thanksgiving is the busiest travel weekend of the year, with roughly 31.6 million people flying. Sunday was expected to be the single busiest day, with nearly 74,400 flights scheduled, according to American Airlines.

Many holiday visitors changed their travel plans to depart on Saturday to avoid the storm, which could snarl roads from northern Pennsylvania to Boston.

Sunday travel will be wet, and roads could be icy, especially heading west through Pennsylvania, where snow may accumulate in the mountains.

Airports are likely to be dealing with major delays as the major storm that wreaked Thanksgiving havoc across the country heads east. The major airlines issued travel waivers, allowing flyers to switch flights for free for trips out of LaGuardia, Kennedy and Newark airports.

And Monday morning’s commute could be a nightmare, with freezing rain or snow falling as the city heads back to work and school after the long holiday weekend.