Mother Nature gave quite a send-off to the hot temperatures Monday as the sunny weather quickly changed to strong storms.

Clason Point Park had lots of people enjoying the sunny day early Monday afternoon before a pop-up thunderstorm sent them running for cover by the late afternoon.

The first crack of thunder hit the Bronx around 4 p.m., followed by pouring rain. The showers followed multiple days of temperatures over 90 degrees, resulting in power outages citywide.

MORE: Bronx Weather Center

Viral video showed a waterfall-like flood on a stairway at the Grand Concourse-149th Street station as commuters tried to get home.

Many subway riders say the MTA should've been better prepared for the storms.

"They knew the rain was coming. They knew this probably happened before ... they should have some type of steps to prevent it," says commuter Bianca Quinones.

A flash flood watch remains in effect in the Bronx through 8 a.m. Tuesday.