Heat, humidity, and potential storms return to the Philly region

Well, it was nice while it lasted.

“Unfortunately, we are looking at another return to severe heat conditions,” said Robert Deal, a meteorologist with the National Weather Service office in Mount Holly. And he’s not kidding.

After a brief break from the scorching temperatures and oppressive humidity so often foisted upon the region this month, Friday appears to be bringing back a generous serving of both. The entire Philadelphia region will be under an extreme heat warning and heat advisory from 10 a.m. to 9 p.m., with heat indexes reaching 100 to 108 degrees, according to current forecasts.

Actual temperatures, meanwhile, are likely to top out in the upper 90s, suggesting we could match the 2016 record high of 97 degrees for July 25. Those dangerously high levels of heat and humidity raise the potential for heat-related illnesses, so Deal advised residents to take caution Friday.

“Heat is the silent killer, and it disproportionately affects people who are more vulnerable,” Deal said. “If you have to be outside, take breaks, hydrate, and find shade.”

So far this summer, there have been five heat-related deaths in Philadelphia, city health department spokesperson James Garrow said.

High heat and humidity can also create instability in the air, which may result in some scattered severe thunderstorms Friday — including the possibility of damaging winds, some hail, and brief, heavy downpours throughout the region, forecasts indicate.

As of Thursday evening, much of the region had a marginal risk of severe storms developing, with some areas north of Philadelphia being elevated to a slight risk. Deal said changes were expected due to forecasters’ uncertainty over how quickly a cold front meteorologists are tracking rolls through the region.

If scattered storms do develop, forecasters predict they will hit the area likely later Friday, between 3 and 9 p.m. Damaging wind gusts are expected to be the primary threat.

Saturday morning and afternoon, meanwhile, should be something of a reprieve, with comparatively lower temperatures and drier weather on the docket, Deal said. But things will likely pick back up late Saturday into Sunday, with an uptick in both heat and humidity.

Sunday afternoon is expected to bring high humidity and temperatures into the mid-90s, along with possible showers and thunderstorms that could develop into severe weather, according to the weather service’s forecast.

Early next week is expected to be “seasonably warm with humid weather,” the weather service indicates. As a consolation, Monday could be the driest day, with the chance of showers and thunderstorms increasing as Wednesday approaches.

And for those keeping score at home, it’s not just your imagination — this summer has been a particularly uncomfortable one. The period from June 1 to July 15, in fact, was the region’s third-muggiest start to summer in data going back to 1948, The Inquirer has reported.