Tropical Storm Fay made landfall Friday in New Jersey, about 10 miles north-northeast of Atlantic City, according to the National Hurricane Center.
The storm contains maximum sustained winds of about 45 mph, with higher gusts, but was weakening.
It was moving north at 14 mph and should pick up speed through the evening and overnight as it moves through southeastern New York and western New England.
Minor flooding was reported and there were no immediate reports of significant impact.
As the system moves north over the next 24 hours, it will continue to bring a threat of flooding from New Jersey and Pennsylvania to New York and southern New England.
Fay is expected to weaken to a tropical depression by Saturday morning, the NHC said.
New Jersey Gov. Phil Murphy urged residents to stay indoors for safety.
'Let's all just stay in and have some storm-induced social distancing,' he said, borrowing from a concept more associated with the coronavirus pandemic.
Some New Jersey communities intentionally lowered their lakes' water levels ahead of the storm, hoping to reduce flooding, Point Pleasant Beach Mayor Paul Kanitra told CNN affiliate News 12 New Jersey.
'We've already proactively lowered our lakes over the last 24 hours,' Kanitra said. 'In storms like this ... there's nowhere for the water to go. So, this is one (step) we have available to proactively prepare.'
White House cites storms as reason for postponing Saturday rally
Showers and thunderstorms are expected Friday night into Saturday in northern New England.
A campaign rally for President Trump, scheduled Saturday in Portsmouth, New Hampshire, has been postponed because of the forecast, the White House said.
A tropical storm warning has been issued for the coasts of Delaware, New Jersey, New York -- including New York City and Long Island -- Connecticut and part of Rhode Island.
The warning means that tropical storm conditions are expected somewhere within the warning area.
'We're going to see some trees down. We're going to see some power lines down. Probably a little bit of beach erosion, and that heavy, heavy rainfall,' CNN meteorologist Chad Myers said.
By 9 a.m., the barrier peninsula community of Ocean City, Maryland, had received more than 4 inches of rain in three hours.
Fay formed off North Carolina's coast Thursday. It is the earliest tropical storm that begins with an 'F' on record. The previous record was set on July 21, 2005.
'Around 6 o'clock tonight, that will be the worst weather you get in New York City. By 11 o'clock ... that weather gets into Boston, Connecticut, all the way through New Hampshire and Vermont,' Myers said.