Forecasters say Winter Storm Juno could dump up to 76cm (30ins) in some parts of New Jersey, Maine and New Hampshire.

All non-emergency vehicles were banned in New York City from 23:00 on Monday (04:00 GMT Tuesday) and subway services were suspended. Similar measures were in place in Boston, Massachusetts.

Some 60 million people may be affected.

An emergency has been declared in the states of New York, New Jersey, Connecticut, Rhode Island, Massachusetts and New Hampshire.

Boston, which is forecast to receive some of the highest snowfalls, has also suspended public transport and car travel.

However, some meteorologists in Pennsylvania and New Jersey have downgraded their snowfall predictions, saying there has been less snowfall than initially forecast.

At least one winter storm warning in New Jersey has been cancelled.

In other developments:

1. 6,500 flights in and out of airports along the East Coast cancelled
2. Businesses and schools closed early on Monday
3. Schools not expected to reopen before Wednesday at the earliest
4. Boston is expected to bear the brunt of the storm

`Matter of life and death`

The National Weather Service (NWS) earlier warned that a "potentially historic blizzard" was approaching the north-east.

Glenn Field of the NWS in Taunton, Massachusetts, told the BBC on Monday that the storm would be worse than previously thought.

Hurricane-force winds of up to 80 mph (130km/h) would batter Cape Cod, Nantucket and Martha`s Vineyard, he said.

Mr Field said the heaviest snowfall would come in the early hours of Tuesday, with 15 inches expected between 01:00 and 05:00 (06:00-10:00 GMT), and 30 inches in total in parts of Massachusetts.

New York Governor Andrew Cuomo warned residents against violating the driving ban in 13 southern counties of the state.

New York Mayor Bill De Blasio: "This storm... is going to pack a real punch"
"If you are in your car and you are on any road, town, village, city, it doesn`t matter, after 11 o`clock, you will technically be committing a crime.

"It could be a matter of life and death so caution is required," the governor said.

Echoing his words, New York City Mayor Bill de Blasio urged residents to stay out of the way of the 2,300 snowploughs clearing city streets.

"You can`t underestimate this storm. What you are going to see in a few hours in something that is going to hit very hard and very fast."

Similar bans for non-emergency vehicles were enacted in Connecticut and Massachusetts.

"In addition to heavy snow, with blizzard warnings, there`s a big threat of high, damaging winds, and that will be increasing Monday into Tuesday," said Bob Oravec, a National Weather Service forecaster. "A lot of blowing, drifting and such."

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