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HomeWeather news → Flash Flood Warning Issued for Parts of Delaware, New Jersey, and Pennsylvania
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Flash Flood Warning Issued for Parts of Delaware, New Jersey, and Pennsylvania

August 21, 2026 · wweather1 editorial · 1 min read

The National Weather Service in Mount Holly, New Jersey, has issued a Flash Flood Warning for several counties across Delaware, New Jersey, and Pennsylvania following heavy rainfall.

The warning was issued at 8:39 PM EDT on August 20 and remains in effect until 9:45 PM EDT. Trained weather spotters reported flash flooding and water rescues around Delaware County, with rainfall totals measuring between 1 and 2.5 inches.

While no additional rainfall is expected, ongoing flooding impacts will continue as flash flooding is already occurring. The hazard affects small creeks and streams, urban areas, highways, streets, underpasses, and other poor drainage and low-lying locations.

Locations expected to experience flash flooding include Philadelphia, Camden, Wilmington, Newark, West Chester, Gloucester City, Chester, West Deptford, Yeadon, and Westtown.

Affected areas span across New Castle in Delaware; Camden, Gloucester, and Salem in New Jersey; and Chester, Delaware, Montgomery, and Philadelphia in Pennsylvania.

Why it is dangerous and what to do

⚠️ Safety
• Turn around, don't drown when encountering flooded roads.
• Avoid driving through flooded areas, as most flood deaths occur in vehicles.
📊 The numbers, from wweather1 data
Philadelphia: now +19°, Overcast.
That is 4° below the August climate norm.
The record for this date is +34° (1959).
Three-day forecast: 21 August: +25°/+18° · 22 August: +23°/+19° · 23 August: +28°/+20°
The figures are computed automatically from the Open-Meteo/ERA5 archive — no eyeball estimates.

🌍 Weather in nearby cities

📰 Data source: NWS. Forecast and analysis — wweather1, based on Open-Meteo / met.no data.

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