NEW YORK » A nor’easter blustered into New York and New Jersey today, threatening to swamp homes all over again, plunge neighborhoods back into darkness and inflict more misery on tens of thousands of people still reeling from Superstorm Sandy.

Under ordinary circumstances, a storm of this sort wouldn’t be a big deal, but large swaths of the landscape were still an open wound, with many of Sandy’s victims still mucking out their homes and cars and shivering in the deepening cold.

Thousands of people in low-lying neighborhoods staggered by the superstorm just over a week ago were warned to clear out, with authorities saying rain, wet snow and 60 mph gusts in the evening could bring more flooding, topple trees wrenched loose by Sandy, and erase some of the hard-won progress made in restoring electricity to millions of customers.

"I am waiting for the locusts and pestilence next," New Jersey Gov. Chris Christie said. "We may take a setback in the next 24 hours."

In New Jersey, public works crews worked to build up dunes along the shore to protect the stripped and battered coast, and new evacuations were ordered in a number of communities already emptied by Sandy. New shelters opened.

In New York, police went to low-lying neighborhoods with loudspeakers, encouraging residents to leave. But Mayor Michael Bloomberg didn’t order new evacuations, and many people stayed behind, some because they feared looting, others because they figured whatever happens couldn’t be any worse than what they have gone through already.

All construction in New York City was halted — a precaution that needed no explanation after a construction crane collapsed last week in Sandy’s high winds and dangled menacingly over the streets of Manhattan — and parks were closed because of the danger of falling trees. Drivers were advised to stay off the road after 5 p.m.

By early afternoon, the storm was bringing rain and wet snow to New York, New Jersey and the Philadelphia area. A couple of inches of snow were possible in New York City.

"We’re petrified," said James Alexander, a resident of the hard-hit Rockaways section of Queens. "It’s like a sequel to a horror movie." Nevertheless, he said he was staying to watch over his house and his neighbors.

During Sandy, stores and houses all around him burned to the ground. The boardwalk, flagpoles, light poles and benches were heaved down the block or washed out to sea. His own house was largely spared, except for blown-out windows, but his car was swamped.

"Here we are, nine days later — freezing, no electricity, no nothing, waiting for another storm," Alexander said.

On Staten Island, workers and residents on a washed-out block in Midland Beach continued to pull debris — old lawn chairs, stuffed animals, a basketball hoop — from their homes, even as the bad weather blew in.

Jane Murphy, a nurse, wondered, "How much worse can it get?" as she cleaned the inside of her flooded-out car.

The storm was a few hundred miles off New Jersey this morning and was expected to remain offshore as it traveled to the northeast, passing near Cape Cod. Forecasters said there would be moderate coastal flooding, with storm surges of about 3 feet possible today into Thursday — far less than the 8 to 14 feet Sandy hurled at the region.

The nor’easter’s winds were expected to be well below Sandy’s, which gusted to 90 mph.

Major airlines grounded hundreds flights in and out of the New York area ahead of the storm, causing another round of disruptions to ripple across the country.

Ahead of the nor’easter, an estimated 270,000 homes and businesses in New York state and around 370,000 in New Jersey were still without electricity.

The storm could bring repairs to a standstill because of federal safety regulations that prohibit linemen from working in bucket trucks when wind gusts reach 40 mph.

Authorities warned also that trees and limbs broken or weakened by Sandy could fall and that even where repairs have been made, the electrical system is highly fragile, with some substations fed by only a single power line instead of the usual several.

"We are expecting there will be outages created by the new storm, and it’s possible people who have just been restored from Sandy will lose power again," said Mike Clendenin, a spokesman for Consolidated Edison, the main utility in New York City.

Contributing to this report were Associated Press writers Jonathan Fahey, Tom Hays, David B. Caruso, Meghan Barr, Kiley Armstrong and Jennifer Peltz in New York; Jim Fitzgerald in White Plains, N.Y.; and Angela Delli Santi in Harvey Cedars, N.J. Eltman reported from Garden City, N.Y.