144
Recorded events
1
Direct deaths
17
Direct injuries
$55.9M
Property damage
Flash Flood in Delaware County, Pennsylvania: 144 recorded events between 1996 and 2025. The strongest on record measured 0. That places the county #81 nationally and #7 statewide for this hazard.
Decade by decade
Flash Flood in Delaware County, Pennsylvania: events per decade
Reporting practice changed over time — early decades are undercounted, not calmer.
The busiest decade for flash flood in Delaware County is the 2020s, when 75 of the county's 144 recorded events were logged. Comparing decades is useful for spotting active periods, but the earliest years are thin because systematic reporting for this hazard began later.
Within the Delaware County archive, flash flood makes up 21.5% of all recorded severe weather across 9 hazard types. Nationally the county sits at #81 for this hazard and #7 within Pennsylvania, putting it in the 97.4 percentile of all U.S. counties.
Seasonality
Events by month
Aug is the peak month for flash flood in Delaware County with 50 recorded events, while Jan is the quietest. Seasonality here is a property of the archive as much as the climate: reports cluster where population and spotter networks are densest.
Significant events
Deadliest on record
| Date | Location | Scale | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| Sep 16, 1999 | COUNTYWIDE | 0 | 1 | 14 | $15.0M |
| Mar 22, 2000 | COUNTYWIDE | 0 | 0 | 3 | $0 |
Most recent
Latest recorded events
| Date | Location | Magnitude | Damage |
|---|---|---|---|
| Jul 31, 2025 | BOOTHWYN | 0 | $0 |
| Jul 10, 2025 | CRUM LYNNE STATION | 0 | $0 |
| Jul 10, 2025 | TRAINER | 0 | $5K |
| Jul 9, 2025 | RIDLEY PARK | 0 | $0 |
| Jul 9, 2025 | CHESTER | 0 | $5K |
| Jul 9, 2025 | EAST LANSDOWNE | 0 | $5K |
| Jul 9, 2025 | GLEN MILLS | 0 | $0 |
| Jul 9, 2025 | CHADDS FORD | 0 | $25K |
| Jul 9, 2025 | GLEN MILLS | 0 | $30K |
| Jul 9, 2025 | MARKHAM | 0 | $0 |
Other hazards here
More from Delaware County
- Thunderstorm Wind 331
- Hail 62
- Flood 49
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Heavy rain caused flash flooding along Cobbs Creek and other small streams particularly in the eastern half of Delaware County. Many water rescues from trapped vehicles occurred. Hardest hit was Haverford Township. Doppler Radar storm total estimates reached between 3 and 4 inches in the northeast part of the county. ||In Haverford Township, an emergency disaster was declared. Homes bordering Cobbs Creek and its tributaries were damaged. On Eagle Road, cars were submerged and homes were surrounded by water. Roads and bridges on Hathaway Lane were damaged. Homes and vehicles on Wynnefield Drive were flooded. Six roads in the township were flooded. In Darby Borough, flood waters from the Darby Creek washed away a portion of McDade Boulevard. Ten residents were evacuated from Springfield Road. Roadway and basement flooding also occurred in Lansdowne Borough and Chester City. The precipitation event total at the Philadelphia International Airport was 1.59 inches.
A water rescue from a stranded vehicle took place near the intersection of Industrial Highway and Saville Avenue in Eddystone. Another water rescue from a vehicle took place near the intersection of Eddystone Avenue and East Fourth Street in Eddystone.
A water rescue took place at the intersection of Sugartown Road and Morris Road in Radnor Township. Also, there was widespread roadway flooding in Radnor Township with multiple vehicles trapped in the flood waters. There was a rockslide on Strafford Avenue near Lancaster Avenue.
Quick answers
Frequently asked
How many flash flood events are on record in Delaware County, Pennsylvania?
144 flash flood events are recorded in Delaware County between 1996 and 2025, causing 1 direct deaths.
What is the strongest flash flood recorded in Delaware County?
The strongest flash flood on record in Delaware County measured 0.
Where does the flash flood data for Delaware County come from?
All events come from the NOAA/NCEI Storm Events Database, the federal public-domain archive of severe weather reports. Dates are UTC, damage is as reported and not inflation-adjusted, and the most recent entries may still be revised.
Cite this page
“Flash Flood in Delaware County, Pennsylvania.” Severe Weather History. severeweatherhistory.com/county/pennsylvania/delaware-county/flash-flood/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.