Delaware County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Delaware County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every storm within 100 miles

1. Tropical storms and hurricanes (34 kt or more, still tropical) at closest approach. Post-tropical remnants with gale-force winds are listed but not counted. Direct: track within 50 miles; near: within 100 miles. Distance is measured to the county boundary for counties and to the city centre for cities, using positions interpolated hourly between HURDAT2 fixes.

National Hurricane Center HURDAT2, 1851 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

High tide flooding

1. High tide flooding days are days on which a NOAA tide gauge recorded water at or above NOAA's minor flood threshold, set from the gauge's tide range, counted by meteorological year (May to April). These are the counts in NOAA's annual high tide flooding reports; they are not National Weather Service flood stages. Years with less than 80 percent of data are left out.

NOAA CO-OPS high tide flooding counts, through April 2026, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

More event types since 1996

Costliest events since 1996

1. Sep 16, 1999Flash Flood$15.0 million
   National Weather Service narrative

   Hurricane Floyd battered Eastern Pennsylvania (especially Southeast sections around Philadelphia) on September 16th and brought with it torrential and in some places record breaking rains and damaging winds. The hurricane caused widespread flash flooding as storm totals averaged around six inches in the Poconos and Berks County, eight inches in the Lehigh Valley and from eight to twelve inches in the Greater Philadelphia Metropolitan Area. Six people died directly from the hurricane - four drownings and two persons were hit by trees. The hurricane also indirectly contributed to the death of about seven other persons. About 40 persons were seriously injured. There were hundreds of…

2. Sep 1, 2021Flash Flood$15.0 million
   National Weather Service narrative

   Widespread flash flooding occurred in Delaware County with numerous road closures. Many creeks in the county overflowed their banks, including Chester Creek, Ridley Creek, Crum Creek and Cobbs Creek.

3. Sep 1, 2021Flash Flood$15.0 million
   National Weather Service narrative

   Widespread flash flooding occurred in Delaware County with numerous road closures. Many creeks in the county overflowed their banks, including Chester Creek, Ridley Creek, Crum Creek and Cobbs Creek.

4. Aug 1, 2004Flash Flood$10.0 million
   National Weather Service narrative

   Slow moving thunderstorms with torrential downpours caused flash flooding of streams as well as widespread poor drainage flooding in eastern Delaware County. Doppler Radar storm total estimates reached between 5 and 6 inches. Hardest hit were Haverford and Upper Darby Townships as well as Darby Borough. States of emergencies were declared in Darby and Upper Darby. About 660 residents were evacuated from the three municipalities. One hundred forty-two homes, seventy-seven apartments and sixty-nine businesses suffered major damage. In addition, about 400 other homes and 50 other businesses suffered minor damage. Furniture, appliances, household goods and food were all damaged or…

5. Sep 18, 2003High Wind, Delaware$5.2 million
   National Weather Service narrative

   Tropical Storm Isabel produced strong power outage producing winds, moderate tidal flooding along the Delaware River and stream flooding in Chester County. Isabel made landfall as a hurricane near Drum Inlet, North Carolina around 100 p.m. EDT on the 18th and weakened as it tracked farther inland. At one time in its life cycle, it was a powerful Category 5 hurricane when it was north of the Leewood Islands. Winds gusted up to 60 mph in Eastern Pennsylvania and downed countless numbers of trees, tree limbs and power lines. It was the worst outage on record for PECO Energy in southeastern Pennsylvania. About 572,425 of its customers lost power. This exceeded the outages that…

6. Oct 1, 2010Flood$5.0 million
   National Weather Service narrative

   Flooding along the Darby Creek in Darby Borough was described as the heaviest since Hurricane Floyd. Dozens of families were evacuated and sought shelter at the Mercy Fitzgerald Hospital. People were rescued from the second floor windows on Springfield Road. Water was six to seven feet deep at the intersection of Springfield Road and MacDade Boulevard. A few homes in the borough were severely flooded as well as one automobile parts store. Major flooding also occurred along the entire length of Chester Creek from Thornbury Township into Chester City. About sixty homes were damaged in Chester City. Upland and Brookhaven also had flooding along the Creek. There were about 100 county…

7. Feb 9, 2010Winter Storm, Delaware$2.5 million
   National Weather Service narrative

   For the second time within a week a major winter storm affected Eastern Pennsylvania on the 10th and 11th and smashed seasonal snowfall records in the Philadelphia area. Snowfall averaged one to two feet with some locally higher amounts in the Philadelphia northwest suburbs. ||Around the local Philadelphia area, snow began during the early evening on the 9th. As warmer air moved in aloft, the snow changed to sleet and freezing rain between 3 a.m. and 6 a.m. EST on the 10th. Surface temperatures responded slower and the sleet and freezing rain changed over to rain during the morning of the 10th. Some sleet mixed in from time to time. As the low pressure system moved northeast of…

8. Jun 23, 2015Thunderstorm Wind$2.5 million
   National Weather Service narrative

   Chester City was also hard hit by the powerful macroburst associated with the line of severe thunderstorms. About twenty homes and buildings were condemned because of wind damage including fallen trees. Buildings along the Avenue Of The States as well as trees within city parks were particularly hard hit. A tractor-trailer along Interstate 95 was overturned by the severe thunderstorm. the driver was not injured. Wind damage in the city was estimated at 2.5 million dollars.

9. Jan 7, 1996Blizzard, Delaware$1.4 million
   National Weather Service narrative

   The Blizzard of '96, the second coined "STORM OF THE CENTURY" of this decade brought record breaking snow to most of Southeast Pennsylvania and paralyzed the region for several days, caused most municipalities to exceed their annual snow budgets during this one storm, caused several building collapses and caused directly or directly 42 deaths and countless injuries. Six persons died of hypothermia, 4 in Philadelphia, 1 in Delaware County and 1 in Lehigh County. Some were homeless persons, but one woman in Allentown accidentally locked herself out of her home. Twenty-nine persons suffered heart attacks and died while shoveling snow, using snowblowers or trying to walk in the deep…

10. Jun 23, 2015Thunderstorm Wind$1.0 million
    National Weather Service narrative

    An extremely powerful macroburst associated with a severe thunderstorm cut a swath of wind damage across the eastern side of Aston Township to the east of Concord Road. Peak wind gusts were estimated to reach 85 mph. Shingles and siding was ripped from homes as well as numerous homes that were struck by fallen trees. About fifteen homes were condemned in the township. Wind damage from the macroburst continued southeast through Chester City.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

104°FJul 3, 1966

All-time low

−7°F2 times, most recently Jan 22, 1984

Warmest night

83°F2 times, most recently Jul 23, 2011

Coldest day

6°FJan 19, 1994

Wettest day

8.02 inJul 28, 2013

Snowiest day

27.6 inJan 7, 1996

Hottest year

2012mean 58.9°F

Coldest year

1963mean 52.0°F

Wettest year

201164.33 in

Driest year

196529.34 in

Snowiest season

78.7 in2009-10

Station Phila International Airport (USW00013739), 7 ft elevation, 7.3 miles from the population centre. Daily records from 1940 to October 26, 2026; 100.0% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00013739.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Tide gauges NOAA CO-OPS high tide flooding counts, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.