Flash flooding possible Monday in Philadelphia area as rain replaces extreme heat. Here's the forecast.

Rounds of heavy rain and thunderstorms are expected Sunday night into Monday in the Philadelphia area, with the greatest concern being flash flooding. 

A flood watch remains in effect through 8 p.m. Monday for the I-95 corridor and areas northwest, where localized rainfall totals of 3 to 4 or more inches and rainfall rates over 2 inches per hour could lead to significant flooding, especially in urban and low-lying locations.

Strong to severe thunderstorms are also possible through early Monday, mainly from the I-78 corridor south, including the Philadelphia metro area, South Jersey and Delmarva. Damaging wind gusts are the primary severe threat.

There will be some street flooding, so remember: Turn around, don't drown. Less than 2 feet of water can float your car and carry it away. Power outages are also possible Sunday night and into Monday morning.

NEXT big change

Monday will be much cooler than average, with highs only in the upper 70s, but there is a significant chance of heavy rain and flash flooding.

Several waves of storms with tropical downpours will cross the area, and some of us will see an additional 2 to 4 inches of rain for a grand total of 3 to 5 inches between Sunday evening and Monday night.

Here's your 7-day forecast:

Monday: NEXT Weather Alert for flooding. High 79, low 74.

Tuesday: A shower or two. High 80, low 68.

Wednesday: Finally a break. High 83, low 70.

Thursday: Scattered storms. High 90, low 70.

Friday: Scattered storms. High 91, low 75.  

Saturday: A rumble? High 85, low 73.

Sunday: Mostly sunny. High 87, low 70.