The Philadelphia area is bracing for another set of potentially severe thunderstorms that are expected mark the end of fourth heat wave of summer.

The storms are the vanguard of a cold front that, despite its name, will only cool things off by a few degrees and will do little to diminish the humidity.

The National Weather Service forecast for Philadelphia is calling for a high of 90 degrees, which technically would make Wednesday the fifth day of the heat wave, but AccuWeather is predicting it will only get to 89, a degree short of what’s needed for the heat wave to claim another day.

Early Wednesday afternoon, the weather service issued a severe thunderstorm watch for the East Coast from Washington. D.C. to Boston and a flash flood warning for Philadelphia and areas along the Delaware River. Expect thunderstorm warnings for particular areas to appear throughout the afternoon.

The weather service says damaging winds and torrential downpours are the thunderstorms’ biggest threats.

The latest round of potentially damaging storms comes a little more than a week after severe thunderstorms ripped through the Philadelphia area, knocking out power to tens of thousands of customers and closing the PATCO High Speed Line’s Ashland and Lindenwold stations for two days.

There’s a chance of thunderstorms in the forecast into Saturday with daytime highs in the upper 80s and overnight lows around 70.

It will be a bit cooler at the Jersey Shore, where storms are not expected to arrive until after 5 p.m. There is a moderate risk of rip currents at the Shore and Delaware beaches, the weather service said. When there is a moderate risk of rip currents, you should check with local beach patrols before going into the surf, be sure to swim within sight of a lifeguard, and never swim alone or at night.