Torrential downpours that caused flash flooding in New York City on Friday reflect a "new normal" due to the effects of climate change, New York Governor Kathy Hochul warned on Saturday, as the city began drying out after one of its wettest days ever.

Almost eight inches (20 cm) of rain fell in some parts of the most populous U.S. city, enough to enable a sea lion at the Central Park Zoo to swim briefly out of the confines of her pool enclosure.

While the risk of flooding in the city had receded by midday Saturday, a municipal hospital in the borough of Brooklyn said it would evacuate all patients and staff following a power failure on Friday.

NYC Health + Hospitals/Woodhull had switched to backup power after Friday's neighborhood outage, but repairs will require the power to be shut off entirely for several days, hospital officials said. The facility was transferring its 120 patients to other hospitals on Saturday, a process expected to take eight hours.

The intense rainfall turned some streets into rivers, stranding buses and cars for hours, and forced some subway and commuter rail lines to shut down. Flights were delayed or canceled, and one terminal at LaGuardia Airport was evacuated.

"This is unfortunately what we have to expect as the new normal," Hochul said.

A state of emergency, which allows faster allocation of resources to deal with a crisis, will remain in effect for the next six days, Hochul said. No fatalities were reported as a result of the storm.

President Joe Biden was briefed on the flooding on Friday and Saturday, and the Federal Emergency Management Agency was prepared to assist if needed, according to the White House.