A flash-flood watch is in effect for the region, the National Weather Service says.
The flash-flood watch is in place for Bucks, Chester, Delaware, Lehigh, Montgomery, Northampton and Philadelphia counties until 12:01 a.m. Wednesday, the NWS said.
Rain and thunderstorms are in the forecast for Monday and Tuesday. Up to 3 inches of rain could fall in a short time period, and "flooding of roadways and areas of poor drainage is possible," the NWS said.
Additionally, streams, creeks and rivers may rise very quickly.
The NWS says to be cautious if you live in a flood-prone area.