Tens of millions of people across the north-eastern US are in the path of a powerful storm bringing coastal flooding, power cuts, travel chaos and cancelled stadium events.

The so-called nor'easter is bringing "dangerous coastal flooding and beach conditions, strong winds and heavy rainfall" to areas including New York City and Boston on Saturday, the US National Weather Service (NWS) said.

States of emergency have been declared in New York and New Jersey, both of which faced a coastal deluge in some areas. Rain and strong winds are forecast from Virginia to Maine.

In Brooklyn, a man was killed by a falling tree, the BBC's US partner CBS News reported.

The nor'easter has caused widespread power cuts. More than 100,000 households, nearly all in the northeast US, have lost electricity, according to tracker PowerOutage.

The Federal Aviation Administration recommended air passengers check with airlines about their flight status. More than 2,400 flights have been delayed and another 1,199 grounded, according to FlightAware.

Saturday's full moon is projected to worsen coastal flooding. Streets and homes were inundated with floodwater in the coastal New Jersey communities of Surf City and Manasquan on Saturday.

"I urge all New Jerseyans to take this storm seriously, stay alert and follow local guidance," Governor Mikie Sherrill said.

NWS said in its alert: "Prepare immediately for significant inundation in low-lying areas near the shore, including roads underwater and impacts to homes and businesses."

In New York, officials are warning of wind gusts of up to 55mph (86km/h) throughout the weekend, leading to downed trees and power lines.

"Don't travel if you don't have to," NYC Mayor Zohran Mamdani told residents in a video message. "Do not drive or walk through floodwater."

In the Boston area, the Red Sox moved the last game in their series against the Chicago Cubs to Sunday afternoon in Florida.

A professional football match between Red Bull New York and St Louis City SC was also cancelled.

The Global Citizen Festival concert in New York City's Central Park, which was to be headlined by Lauryn Hill, Wyclef Jean and John Legend, will not go ahead.

Ed Sheeran's Boston concert was also among events called off due to the weather.

Sheeran's concert at the Gillette Stadium in the Boston area was cancelled for safety reasons, the venue said.