The north-eastern US states of New York and New Jersey have declared states of emergency as a huge winter storm sweeps in, threatening blizzard conditions.
Schools are closed and thousands of flights have been cancelled.
The conditions caused German Chancellor Angela Merkel to postpone a trip to Washington to meet President Trump.
With winds of up to 60mph (100km/h), Winter Storm Stella is likely to cause severe disruption for commuters across many parts of the north-east on Wednesday morning, forecasters say.
In all, about 31 million people across America are now under a blizzard warning.
A 24-hour blizzard warning was issued by the US National Weather Service from midnight (04:00 GMT Tuesday) for New York, Connecticut and New Jersey.
Winter storm warnings were also posted from eastern West Virginia to Maine.
"During its height we could see snowfall rates of 1-3 inches (2.5-7.6cm), even up to four inches per hour," said Alan Dunham, a meteorologist based in Taunton, Massachusetts.
More than 6,500 flights have been cancelled, tracking service FlightAware reported, with airports in New York, Washington, Boston, Baltimore and Philadelphia worst hit.
Schools will be closed on Tuesday in New York, Providence, Rhode Island and in some towns across Massachusetts and Connecticut.
Declaring a state of emergency, New York Governor Andrew Cuomo said commuters should expect road closures, delays and cancellations.
"I strongly urge everyone to limit unnecessary travel on Tuesday and if you must drive, please plan ahead, be careful, and stay safe," he said in a statement.
New Jersey Governor Chris Christie also declared a state of emergency and ordered all state employees not involved in the response to stay at home.
Mrs Merkel's visit was planned for Tuesday and has been rescheduled for Friday.
The impending storm also forced Irish Taoiseach (Prime Minister) Enda Kenny to cut short a visit to Boston and head to Washington a day early by train.