High heat and humidity return to Philly region, but a break is on the horizon
Temperatures in the mid and upper 90s are expected through the middle of the week.
Dangerous heat and humidity are again blanketing the Philadelphia region, with temperatures expected to reach into the mid- and upper 90s through the middle of the week — and it will feel like we’re surpassing triple digits.
And yet, there is hope. Come Friday, we’re likely to get a well-deserved break following a bout of showers and thunderstorms that could chop the high down to a downright balmy 80 degrees or less. Until then, a heat advisory is in effect for much of the region through 8 p.m. Wednesday.
“People will be looking forward to it, I think,” said Patrick O’Hara, a meteorologist with the National Weather Service office in Mount Holly.
Rightfully so. The region has experienced several heat waves this summer, and in July alone, we’ve seen 19 days above 90 degrees so far. Overall, the temperature for the month is 2 or 3 degrees above normal, O’Hara said, with the weather giving us “little breaks here or there.”
Much of July‘s seemingly intractable hot weather is being fueled by a “heat dome” that has been lingering in the eastern United States for about a month. These slow-moving, high-pressure systems are a weather phenomenon in which a section of high pressure over an area traps heat and humidity for an extended period of time.
That often results in day after day of high temperatures and stifling humidity. But while heat domes are uncomfortable and can result in dangerously hot weather, they are not exactly unusual for this time of year.
“July is the month for it,” O’Hara said. “It’s really kind of typical late summer weather for the Delaware Valley.”
This current round of heat, of course, follows a sweltering end to last week, which saw temps at Philadelphia International Airport hit 98 degrees Friday — a record for a July 25, topping the previous 2016 record of 97. With temps that high, meteorologists have warned vulnerable folks to stay out of the sun unless necessary, and to take frequent breaks and hydrate if keeping out of the heat is not an option.
That advice is equally applicable this week. The weather service reported a high of 94 degrees Monday afternoon for Philadelphia, with the heat index reaching as high as 98. Tuesday and Wednesday are likely to be even warmer, with the mercury climbing as high as 98 degrees, and heat indexes hitting 103. Nighttime lows are expected to be in the mid- to high 70s, so relief overnight isn’t likely.
O’Hara said forecasters expect the heat to finally break around Thursday with the arrival of showers and thunderstorms. It was not immediately clear how severe those storms could be, he said, but it’s possible the “drums bang louder” about effects like possible flash flooding as the week wears on, he added.
The heat dome blanketing the area, meanwhile, will likely begin to travel back to the Western states, leaving the Philadelphia region with significantly cooler temperatures, O’Hara said. Friday, for example, could see temps top out at 77 degrees, according to weather service forecasts — and similarly cooler weather in the low 80s could last at least through the weekend.
By Friday, that will be a welcome change. And knowing we have a break on the horizon may make this current bout of heat a little easier to bear.
“There is at least an end to it,” O’Hara said.