After a historically cold Memorial Day weekend — with temperatures significantly chillier than they were on Christmas — strong and possibly severe storms are expected starting late Wednesday night that could set off some flooding, forecasters say.

With a plume of subtropical, ultra-moist air expected to overspread the East, the government’s Weather Prediction Center has the Philadelphia region and most of New Jersey under an “excessive rainfall” risk, with rain expected to continue into Friday.

“There’s definitely going to be storms and showers,” said Brian Wimmer, meteorologist with AccuWeather Inc.

Based on projections of the available moisture and the atmosphere’s behavior, it’s possible that the National Weather Service in Mount Holly will end up issuing its first flash flood warnings in nine months, said meteorologist Nicholas Carr.

Yes, it’s been a while: The office never has gone this long without issuing such a warning, he said.

At least it will feel like June with temperatures near 80 Wednesday, Thursday, and Friday.

» READ MORE: Jersey Shore faithful still show up despite pretty terrible Memorial Day Weekend weather

The folks who braved the Shore during the weekend could have used some of that. Philadelphia and Atlantic City smashed long-standing records for low maximum temperatures.

Exactly one week after setting daily records for high temperatures, Atlantic City International Airport didn’t make it past 54 on Saturday or Sunday, its lowest maximum temperatures for a May 29 or May 30 ever, and 8 degrees cooler than it was on Christmas Day. Those who endured perhaps merited souvenir T-shirts. “Or sweatshirts,” said Wimmer.

» READ MORE: A rainy, blustery Christmas Eve storm for Philly area, just as Santa’s sleigh is set to soar

In Philly, Sunday’s high of 53 was 12 degrees lower than that of Dec. 25, and Saturday’s, 54, unseated a 137-year-old record. Exhalation clouds usually aren’t the stuff of Memorial Day weekends.

Not that the brooding atmosphere needed any more clouds.

Strong onshore winds from the northeast imported those raw winds overlying the cool waters into early Saturday afternoon, and then dense, sun-screening cloud cover and lingering rain from a slow-motion upper-air system locked in the chill, meteorologists said.

» READ MORE: Summer arrives in Philly; 90-plus temperatures possible Sunday

Wimmer said Saturday’s record in Philadelphia was especially impressive since it beat the old one by a full 6 degrees. Given that official temperature tracking began in the 1870s in the city, most of the time, records are bested by only a degree of two.

Carr said he even was tempted to turn on his heat, but held his fire.

“I can’t do it in May,” he said.