Philly prepares for heat wave as temperatures in the 90s expected to linger through at least Saturday

A heat advisory is in effect through Wednesday as temperatures are expected to reach 100 degrees at least once throughout the week.

A pedestrian walks across the street in Kensington where a fire hydrant is bursting with water on July 28, 2023.Read moreAllie Ippolito / Staff Photographer / Allie Ippolito / Staff Photograp

by Beatrice Forman

Updated June 17, 2024, 3:19 p.m. ET

Published June 17, 2024, 9:31 a.m. ET

It’s going to be a scorcher, Philly.

The summer’s first official heat wave kicked off Monday afternoon when temperatures reached 90 degrees just after 3 p.m. Ninety-plus degree heat will persist through at least Saturday, according Sarah Johnson, a meteorologist with the National Weather Service at Mount Holly.

Temperatures are expected to rise gradually throughout the week, with the “worst of it” coming Thursday through Saturday, said Johnson.

Temperatures are predicted to kiss 100 degrees on Thursday (the first official day of summer) and Friday, but humidity will likely make it feel much, much hotter.

The weather service has issued a heat advisory for Philadelphia and the surrounding counties through Wednesday, and an excessive heat watch has been extended through Saturday night. The city has yet to declare a heat emergency. Officials have previously said early-season emergencies are triggered by three consecutive days of 98-degree temperatures or two days of temps higher than 101 degrees.

The city’s has designated 14 libraries as cooling centers for the summer, but they only act in that role once a heat emergency has been declared.

What makes this hot spell particularly notable, said Johnson, is its persistence: The highs are very high, and the lows — well — aren’t actually low. Monday night’s low is forecast to be in the sensible 60s. After that, they will hover in the mid-70s.

“There’s not going to be a lot of relief,” said Johnson. “And it’s pretty early in the season, so people aren’t quite acclimated to the heat.”

The last time temperatures in Philly reached 100 degrees was summer 2012, making this the city’s longest stretch without breaking the triple digits in over a century. Thursday has a chance to break that record, and another: the highest recorded temperature on a June 20 summer solstice in Philly, set at 98 degrees during the Dust Bowl in 1931.