Severe storms hammered parts of the tri-state area Monday afternoon into the late evening hours, flooding City subways, prompting dozens of water rescues and triggering a state of emergency in hard-hit parts of New Jersey.

Numerous flash floods had been reported across New York, New Jersey and Connecticut, closing roads and highways, submerging cars, and stranding motorists, according to the National Weather Service. Metro-North reported suspensions of service on part of the Harlem line, and some delays on the New Haven line, as well, which has since been reopened.

The National Weather Service has issued a Flood Watch for NYC, predicting thunderstorms and potential flash floods with heavy rainfall rates across all five boroughs.

The summer season is among the busiest parts of the year when it comes to air travel, but thousands of flights have been grounded this week after severe inclement weather. Flash flood warnings have been issued in several states to start the week after heavy rainfall.

The National Weather Service is predicting a slight chance of more rain Tuesday, July 15, after torrential rain, flooding Monday in the Lower Hudson Valley.

Humidity levels in the tri–state area have been particularly unpleasant making the hot temperatures feel even warmer and a second heatwave could be on the way