The flash flood threat follows a deadly heat wave that saw triple-digit temperatures reached in the week leading up to July 4.
Heavy rain has already triggered flooding in parts of New York City, Philadelphia, and New Jersey on Monday as multiple rounds of storms swept through the region, breaking the heat wave that gripped much of the area last week.
Just one day after warning New Yorkers about extreme heat and advising them to cool off at pools and cooling centers, New York City Mayor Zohran Mamdani has urged residents to evacuate basement apartments immediately if floodwaters start to rise.
Mamdani also
urged residents to limit travel and stay inside during heavy rain and thunderstorms.
The New York State Division of Homeland Security & Emergency Services warned Monday that storms capable of producing torrential rain will hit certain areas.
"Persistent rain will result in a continued flash flood threat into the overnight hours,” the
agency wrote on X, adding that rainfall totals have reached 3 inches across the lower Hudson Valley and Downstate areas. Showers will likely continue to bring rainfall rates exceeding one inch per hour in several locations.
Meanwhile, ground stops have been issued at major airports across the New York City metro area as thunderstorms move through the region,
according to the Federal Aviation Administration (FAA). Travelers are experiencing delays of up to an hour at Newark Liberty International Airport, John F. Kennedy International Airport, and LaGuardia Airport due to heavy rain and strong storms in the tri-state area, prompting flood watches and travel advisories.
In New Jersey, two people were trapped under debris at the BJ’s Wholesale Club in Ocean Township, New Jersey, after rain caused part of the warehouse's roof to collapse. They were able to escape, and nobody else and no injuries were reported, according to local law enforcement.
Additionally, a flood watch remains in effect through 2 p.m. Tuesday for periods of heavy rain all across southeastern Massachusetts, Rhode Island, and Connecticut.
Connecticut Gov. Ned Lamont said on Monday that he held a
statewide meeting with officials to prepare for potential flooding.
Severe storms have already left thousands of homes without power, and repairs in certain areas may take several days due to the scale of the damage, Lamont said.
According to NWS, most flash floods are triggered by slow-moving thunderstorms or repeated storms that pass over the same area. They can develop quickly—often within six hours or less after heavy rain begins—making them especially dangerous. Mountain streams and rivers, urban neighborhoods, low-lying areas, storm drains, and culverts are among the places most vulnerable to flash flooding.
The Associated Press contributed to this report.
