New York City Mayor Bill de Blasio declared a state of emergency on Wednesday night due to what he called a "historic weather event" with record-breaking rain across the city leading to flooding and dangerous conditions on the roads.

Nearly all New York City subway lines were suspended late on Wednesday as the remnants of tropical storm Ida brought drenching rain and the threat of flash floods and tornadoes to parts of the northern mid-Atlantic, CNN reported earlier.

All non-emergency vehicles were banned from New York City's streets until 5am on Thursday due to the weather, city authorities said on Twitter.

At least five flash-flood emergencies were issued on Wednesday evening by the National Weather Service, stretching from just west of Philadelphia through northern New Jersey.

Earlier in the night, New Jersey Governor Phil Murphy also declared a state of emergency in response to Ida.

Storm damage from Ida astounded officials three days after the powerful hurricane pounded southern Louisiana, as reconnaissance flights revealed entire communities devastated by wind and floods.

Tornadoes spawned by the storm ripped through parts of Pennsylvania and New Jersey, images on social media showed. At least nine homes were destroyed in Mullica Hill, New Jersey, Philadelphia's NBC10 television station reported.

New Jersey's Newark Liberty Airport said on Twitter it was experiencing "severe flooding". It said it resumed "limited flight operations" close to midnight after all flight activity was suspended late on Wednesday.

New York City also experienced flooding, with social media images showing water gushing over subway platforms and trains.

Subway service was "extremely limited" due to the flooding, the Metropolitan Transit Authority (MTA) said.

First responders evacuated people from the subway system, the acting chair and CEO of the MTA, Janno Lieber, said in a statement.

The mayor urged people to not go outside.

"Please stay off the streets tonight and let our first responders and emergency services get their work done. If you're thinking of going outside, don't. Stay off the subways. Stay off the roads. Don't drive into these heavy waters. Stay inside", he said on Twitter.