Hour-By-Hour Climb To 109 Heat Index In Eastern PA

EASTERN PENNSYLVANIA — The Philadelphia region is bracing for what is expected to be one of the hottest days of the year, with temperatures that feel as high as 109 degrees.

An excessive heat warning is in effect for the Philadelphia region through 8 p.m.

The heat index — what the temperature feels like to people as heat and humidity combine — could reach as high as 109 degrees in parts of the Philadelphia region, according to the National Weather Service.

Monday's heat comes after days of oppressive conditions: Temperatures in Philadelphia did not go under 80 degrees overnight, following extreme heat Sunday. By 10 a.m. Monday, it was already 89 degrees with a heat index of 96 degrees, according to the National Weather Service.

Here is the hour-by-hour forecast for Philadelphia, with heat index values:

The extreme weather has prompted the closures of some coronavirus testing sites, including Montgomery County's community testing sites in Lansdale, Norristown, Pottstown, and Willow Grove.

While Monday is expected to be the worst of the heatwave, "dangerously hot and humid conditions are expected to return on Wednesday and Thursday," the Weather Service said.

Additional heat advisories could be forthcoming.

The National Weather Service has the following tips to get through the heat wave:

• Reschedule outdoor activities to the early morning or evening hours.
• Wear lightweight, loose fitting clothing, and drink plenty of water.
• If at all possible, stay in an air-conditioned building and check on others who may be susceptible to the extreme heat, especially the elderly.

Here is the full forecast:

Today: A slight chance of showers and thunderstorms after 1pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 106. West wind around 10 mph. Chance of precipitation is 20 percent.

Tonight: Partly cloudy, with a low around 73. Northwest wind 5 to 10 mph.

Tuesday: Mostly sunny, with a high near 95. North wind around 5 mph becoming west in the afternoon.

Tuesday Night: A chance of showers and thunderstorms after 2am. Mostly cloudy, with a low around 74. Calm wind. Chance of precipitation is 30 percent. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Wednesday: Showers and thunderstorms likely, mainly after 2 p.m. Mostly cloudy, with a high near 93. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 60 percent. New rainfall amounts between a quarter and half of an inch possible.

Wednesday Night: Showers and thunderstorms likely, mainly before 8pm. Mostly cloudy, with a low around 75. Chance of precipitation is 60 percent. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Thursday: A chance of showers and thunderstorms after 2pm. Partly sunny, with a high near 92. Chance of precipitation is 40 percent.