Philadelphia weather: Humid Sunday ahead of severe nighttime storms, flood risks

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FOX 29 Philadelphia
Published July 5, 2026 9:28 AM EDT
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Philadelphia weather: Sunday morning forecast

Temperatures drop to low 90s on Sunday ahead of more storms during the evening hours.

The Brief

    • While most of Sunday remains dry with a muggy high in the low 90s, widespread strong storms, heavy rain, and lightning will start around sunset and peak near 10 p.m.
    • Monday brings a break from the 90s with temperatures holding in the 70s, but high humidity will fuel slow-moving storms capable of dumping torrential rain.
    • Monday's storms pose a flash flooding risk, particularly for the evening commute.

PHILADELPHIA - Sunday may offer a slight break from the scorching heat, but an active stretch of weather is on the horizon for the Delaware Valley, including severe nighttime storms and a flash flooding threat for the Monday evening commute.

Sunday forecast

Timeline:

While Sunday afternoon will remain mostly dry, the atmospheric setup is primed for a stormy shift after dark.

Temperatures are expected to top out in the low 90s. While still hot, it’s a slight step down from Saturday's intense heat. Morning temperatures started in the 70s with overwhelming humidity, meaning it will feel thick and uncomfortable all day. Highs will hover in the 80s by the evening, but conditions will stay dry until closer to sunset.

  • Through 2 p.m. Completely dry across the region with a mix of clouds and sun.
  • Around 4 p.m. A few isolated, pop-up showers may develop, specifically south of Doylestown in Bucks County and across Princeton in Mercer County.
  • After sunset: Storms will begin about an hour north of Philadelphia.
  • Around 10 p.m.: Expect widespread, heavy rain and frequent lightning across the immediate Philadelphia area. While South Jersey, Delaware and the shore won't see the worst of it until Monday.

A heat advisory has been issued from 8 a.m. to 8 p.m. on Sunday for the Philadelphia region.

Monday flooding

What we know:

The relentless 90-degree heat vanishes on Monday, but is replaced by a "murky," cloud-covered day.

The primary concern for Monday is flash flooding. Since the air remains incredibly humid, developing storms will move very slowly, essentially sitting over the same areas and dumping massive amounts of rain. A flood watch has been issued from 2 p.m. Sunday to 8 p.m. Monday.

The heaviest downpours are timed right around the afternoon and evening commute. If you have to drive home from work on Monday, prepare for slow travel and localized pooling on the roadways.

Afternoon temperatures will struggle to leave the 70s. It will still feel humid and sticky, but it is a significant break from the mid-summer heat.

What's next:

More 80-degree days on Tuesday and Wednesday before the heat returns on Thursday with temperatures in the 90s, and another possible heatwave.

The Source: Information from this article was provided by the FOX 29 Weather Team.

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