Flash Flood Warning Issued for Southeastern Pennsylvania Counties
This alert is no longer in effect.
NOAA issued it on August 17, 2026, 7 days ago. Warnings of this kind stay in effect for hours to a few days, so this page is a historical record of what was issued, not a current warning. For conditions where you are right now, check weather.gov (US), weather.gc.ca (Canada), the Met Office (UK), or the Bureau of Meteorology (Australia).
Areazine synthesizes this NWS weather alert directly from NOAA's official public data feed. See our methodology for full source attribution and refresh cadence.
NWS Mount Holly has issued a Flash Flood Warning for Chester, Delaware, Montgomery, and Philadelphia counties in Pennsylvania until 3:30 AM EDT August 17.
Read this weather record in 30 seconds
- Record type
- Flash Flood Warning
- Affected area
- Southeastern Pennsylvania
- Issued
- August 17, 2026
- Issuing authority
- NWS Mount Holly NJ
Flood notices turn on location and timing. Treat the named area as this record's scope; do not assume nearby counties, parishes, or waterways were included.
Record status: historical. It was issued 7 days ago; use the issuing agency's live warning service for current conditions in Southeastern Pennsylvania.
Alert Details
Flash Flood Warning issued by NWS Mount Holly NJ. Effective from August 16 at 11:21 PM EDT until August 17 at 3:30 AM EDT. Alert type code: FFW.
Affected Areas
Central Chester County, Northern Delaware County, Southern Montgomery County, and Northwestern Philadelphia County in southeastern Pennsylvania. Specific locations include Philadelphia, West Chester, Norristown, Phoenixville, West Norriton, East Norriton, Coatesville, Westtown, Downingtown, Conshohocken, Royersford, and Narberth. Affected highways include Interstate 476 between mile markers 8 and 19, Interstate 76 between mile markers 327 and 338, and Pennsylvania Turnpike between mile markers 305 and 334.
What You Should Do
Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles. Be especially cautious at night when it is harder to recognize the dangers of flooding.
Expected Conditions
Doppler radar indicated heavy rain across the warned area with 1 to 2 inches of rain fallen. Expected rainfall rate is 2 to 3 inches in 1 hour. Additional rainfall amounts of 0.5 to 1 inch are possible. Hazard is flash flooding caused by heavy rain.
Timeline
The warning is in effect from 11:21 PM EDT on August 16, 2026, until 3:30 AM EDT on August 17, 2026.
Original source: NOAA Official Notice ↗
Related Weather Alerts
All Weather Alerts →Nationwide notices with similar length or severity timing 8
Two Areazine-derived peer sets for this NWS weather alert: nearest notices by body length and by same severity near the same agency date. Peers come from other categories so they are not the same-feed Related list above.
Similar body length
Nearest notices by article body length (1,286 characters here).
Similar severity timing
Same severity (high) notices issued closest in time to August 17, 2026.
Frequently Asked Questions
Common questions about this NWS weather alert.