New York City Mayor Bill de Blasio says he will warn New Yorkers that weather disasters will become “much worse” in the future.

“Every attempt at projection, bluntly, is failing us,” he said. “We’re getting projects from the very best experts… that are made a mockery of in a matter of minutes.”

De Blasio said that “we need to start communicating to people that things will be much worse in literally every situation.”

The mayor added that forecasters on Wednesday had predicted three to six inches of rain, which turned “into the biggest single hour of rainfall in New York history, with almost no warning”.

All but one of those who died during the storm in New York City were killed in residential basements, New York City Police Commissioner Dermot Shea has said.

Speaking to reporters on Thursday, Shea said that eight of the nine people confirmed dead were in the borough of Queens, where the live news conference took place.

“It’s an unimaginable loss for New York City and for Queens,” he said.

Shea added that the most recent victim died in a vehicle accident on the Grand Central Parkway, which connects New York City to nearby Long Island.

Image source, NYC Mayor's Office

New York City Mayor Bill de Blasio has just finished a news conference, where he confirmed that nine New Yorkers were killed during the storm.

He said that “the price paid by some New Yorkers was horrible and tragic.

“[Those] are nine people who were alive at this exact moment yesterday.

“There are families in mourning right now. We need to be there for them and for all the New Yorkers right now who are dealing with the results of this horrifying storm,” the mayor added.

He said he expected “maximum” federal aid will be provided to help the city recover.

“People are going through hell right now,” he said. “They need help.”

At least 14 people have now died in New York, New Jersey and Pennsylvania following the remnants of Hurricane Ida.

Eight of the victims were in New York City, and include a two-year-old boy. Some died when they became trapped in flooded basements.

More deaths are expected in Philadelphia where officials have reported “multiple fatalities,” without giving further details.

In New Jersey, five people died in the same apartment complex in the city of Elizabeth.

Officials are asking residents to check on their neighbours as the clean-up effort gets underway.

The BBC's US partner CBS has shared social media footage from the city of Yonkers in New York showing drivers stuck in their cars amid the flash flooding and calling for help.

New Jersey will send a "major disaster declaration request" to the federal government to help it recover from the storm, Governor Phil Murphy said on Thursday.

“This is going to take us some time to dig out of, there’s no question about it,” he said in a news conference on Thursday morning.

The governor also said he plans to speak to US President Joe Biden about federal support, saying it will be a "game-changer" to help the clean-up.

Governor Murphy declined to give more information on how many people have died across the state, saying only that “more than a few folks have passed as a result of this”.

Image source, Reuters

President Biden is due to address the nation later on Thursday, where he is expected to deliver remarks on the White House's response to the damage caused by Hurricane Ida.

In a meeting with the governors of Louisiana and Mississippi on Monday, the president pledged a massive federal response to help states recover from the storm.

“We’re providing any help that you’re going to need,” Biden said. “It is in moments like these that we can see the power of government to meet the needs of people.”

The remnants of once-Hurricane Ida are expected to drift over New England, prompting flood warnings in parts of the region.

According to the US National Weather Service, flood warnings were issued for large parts of New England beginning on Thursday morning, even as the storm drifts away.

The flood warning for southeast New England – which includes Boston – noted that “it may take much of the morning for some of the urban flooding to recede.”

The warning added that some streams and rivers are still rising, with flooding around the waterways likely.

Overnight, a tornado watch was also issued for south-eastern Massachusetts and all of nearby Rhode Island. It has since expired.

People in New York have been sharing dramatic footage of floodwater cascading into subway stations. In this footage from Jefferson Street station in Brooklyn, a man is seen braving the sheets of water to exit the train.

At another station, water was flowing down steps, across the platform and onto the tracks.

It wasn't just subway stations that found themselves under water - a terminal at Newark airport in New Jersey was also flooded. More than 300 flights at the airport were cancelled on Thursday.

Image source, Getty Images

An overnight travel ban has been lifted in New York City but officials are urging people to remain indoors as emergency workers begin to clear-up the city and asses the damage caused to streets and highways.

Mayor Bill de Blasio's office tweeted: "Stay home as much as possible today until conditions improve".

The ban order urging people to remain indoors was issued on Thursday shortly before 01:00 EST (06:00 BST).

More than 100,000 homes began Thursday morning without power in New York, New Jersey, and Connecticut, data shows.

According to information from PowerOutage.us, 40,551 homes were without electricity as of 08:22 EST (13:22 BST).

About half the outages are in Dutchess or Westchester counties.

Two hours earlier, the total number of homes without power stood at over 45,600.

In New Jersey, over 60,000 homes were without power. The outages are mostly located in Sussex, Warren or Hunterdon counties.

Another 17,302 homes are without electricity in nearby Connecticut.

Image source, Getty Images

Laura Trevelyan
BBC World News America presenter

At 8pm on Wednesday night, torrential rain began to fall as the Amtrak train I regularly get between Washington and New York approached New Jersey. Suddenly my phone lit up with flash flooding alerts, and the rainfall intensified, vast sheets of water hammering the side of the train.

"It’s like a car wash", said the cafe car attendant in wonder, as we stopped at Metropark station. Soon came the announcement of flooding on the tracks ahead of us, making it impossible to reach New York.

Passengers scrolled social media, swapping tales of flooding at Newark airport in New Jersey and streets underwater in Brooklyn.

I called my husband at 1am and told him I was stuck. There is no alternate transportation, read a sign at Metropark station. The roads around us were flooded and there was no way out, so I settled in for the night.

At 2am came the announcement that our train was going back to Washington. I changed trains to one bound for New York - which still hadn’t left as of 6.15am.

My husband is driving to get me - though many roads are closed, he says.

This is the new world of extreme weather, severe, exacerbated by climate change. The extent of the rainfall caused by the remnants of hurricane Ida in Louisiana was unexpected, catching forecasters and travellers out.

Image source, Laura Trevelyan

Subway lines across New York City have been forced to close.

Video on social media showed heavy floodwater surging onto platforms and tracks.

Service on the system remains paralysed, despite the city lifting a travel ban at 05:00 local time on Thursday.

New York's Mayor Bill de Blasio tweeted: "If you’re thinking of going outside, don’t. Stay off the subways. Stay off the roads. Don’t drive into these heavy waters."

The storm caused hundreds of flights at New York's Newark, LaGuardia and JFK airports to be cancelled on Thursday, although all have said that now the bad weather has passed, they are cleaning up and preparing to get back to normal operations.

On its Twitter page, external, JFK said 20 flights were cancelled, and Newark airport said more than 300 flights had been grounded.

Travellers are being advised to check the latest with their airlines before heading to the airport.

Image source, Getty Images

Thank you for joining our live coverage of the ongoing flood emergency in New York City and the state of New Jersey.

It is early in the morning on the east coast of America right now. People are waking up to extraordinary images of cars floating in floodwaters, huge waves gushing into subway stations and the news that at least nine people have died, including a two-year-old boy.

We will bring you the latest headlines and developments as they happen.