Delaware County, Pennsylvania
Natural disaster risk, federal disaster history and flood insurance facts.
Delaware County, Pennsylvania has a moderate overall risk from natural hazards in FEMA's National Risk Index. Its risk score is higher than 93% of US counties. It ranks 7th of 67 counties in Pennsylvania. The costliest hazards here are inland flooding, earthquakes and heat waves. FEMA estimates about $135 million a year in expected losses, or roughly $234 per resident. Since 1965 it has been included in 22 federal disaster or emergency declarations for natural events (15 major disasters). The most recent was in September 2021 (remnants of hurricane ida). Fewer than 1 in 100 homes here carry federal flood insurance (1,153 policies). Since 1978, federal flood insurance has paid about $57 million on 3,034 claims here.
FEMA National Risk Index December 2025; OpenFEMA declarations to Nov 6, 2026; NFIP records. Updated November 6, 2026.
Top risks in Delaware County
- Check the FEMA flood map for your address, and ask the seller or landlord about past flooding.
- Price a flood policy now. Most new federal policies take 30 days to start.
- Ask whether an older house is bolted to its foundation.
- Consider separate earthquake insurance where risk is high.
- Check that cooling works before summer.
- Know where the nearest cooling center is.
All 18 hazards
What the ratings mean ›| Hazard | Rating | Score | Expected loss a year | |
|---|---|---|---|---|
| Inland flooding | 94.4 | $74M | ||
| Earthquake | 94.5 | $13M | ||
| Heat wave | 97.6 | $13M | ||
| Tornado | 92.5 | $9M | ||
| Cold wave | 91.5 | $9M | ||
| Hurricane | 88.1 | $6M | ||
| Strong wind | 97.7 | $5M | ||
| Winter weather | 99.2 | $2M | ||
| Lightning | 95.6 | $2M | ||
| Ice storm | 87.0 | $750K | ||
| Coastal flooding | 63.6 | $730K | ||
| Drought | 54.2 | $209K | ||
| Hail | 13.3 | $46K | ||
| Wildfire | 27.7 | $13K | ||
| Landslide | 59.4 | $3K | ||
| Avalanche | 11.4 | $11 |
Scores are percentiles: a score of 90 means higher risk than about 90% of US counties for that hazard. Hazards FEMA does not rate here are left out. Social vulnerability is relatively low and community resilience is very high in FEMA's measures.
Federal disaster history
Recent disasters nationwide ›Declarations by decade
Federal declarations for natural events that included Delaware County. 2020s bar runs to November 2026.
By type
Most recent
Show all 22
Pennsylvania also had 7 statewide declarations that did not name single counties.
Storm history since 1957
Tornado risk by county ›The National Weather Service has logged 693 storm reports in Delaware County since 1957, with 4 deaths and 42 injuries and about $77.8 million in reported damage. The strongest on record here was an F2 tornado on June 29, 1973.
Strongest tornadoes
| Date | Strength | Near | Hurt / killed |
|---|---|---|---|
| Jun 29, 1973 | F2 | – | 0 / 0 |
| Oct 31, 2019 | EF2 | Glen Mills | 2 / 0 |
| Sep 27, 1993 | F1 | Springfield | 0 / 0 |
| Jul 15, 1992 | F1 | – | 0 / 0 |
| Aug 22, 2010 | EF0 | Trainer | 0 / 0 |
Most damaging storms
| Date | Type | Near | Damage |
|---|---|---|---|
| Sep 16, 1999 | Flash Flood | Countywide | $15M |
| Sep 1, 2021 | Flash Flood | Edgemont | $15M |
| Sep 1, 2021 | Flash Flood | Booth Corner | $15M |
| Aug 1, 2004 | Flash Flood | East Portion | $10M |
| Sep 27, 1993 | Tornado | Springfield | $5M |
| Oct 1, 2010 | Flood | Chadds Ford | $5M |
Source: NOAA Storm Events Database, county-based reports through Jul 11, 2026. Tornado records start in 1950, hail and wind in 1955, and floods and other storm types in 1996, so older decades undercount. Damage is in dollars of the year it happened and is often an estimate. Winter storms, heat and hurricanes are logged by forecast zone, not county, so they are not counted here.
Hurricanes and tropical storms
Hurricane risk by county ›Since 1861, 2 hurricanes and 18 tropical storms have passed within 65 miles of the center of Delaware County, 10 of them since 1950. The strongest was an unnamed hurricane in 1878, with top winds near 90 mph about 64 miles away.
Strongest storms nearby
| Date | Storm | Strength | Closest |
|---|---|---|---|
| Oct 23, 1878 | Unnamed | Category 1, 90 mph | 64 mi |
| Sep 16, 1903 | Unnamed | Category 1, 80 mph | 64 mi |
| Aug 28, 2011 | Irene | Tropical storm, 70 mph | 64 mi |
| Jul 13, 1996 | Bertha | Tropical storm, 70 mph | 46 mi |
| Aug 4, 2020 | Isaias | Tropical storm, 65 mph | 52 mi |
| Aug 28, 1971 | Doria | Tropical storm, 65 mph | 60 mi |
Most recent storms
| Date | Storm | Strength | Closest |
|---|---|---|---|
| Aug 4, 2020 | Isaias | Tropical storm, 65 mph | 52 mi |
| Jul 10, 2020 | Fay | Tropical storm, 50 mph | 64 mi |
| Aug 28, 2011 | Irene | Tropical storm, 70 mph | 64 mi |
| Sep 6, 2008 | Hanna | Tropical storm, 50 mph | 46 mi |
| Jul 13, 1996 | Bertha | Tropical storm, 70 mph | 46 mi |
| Sep 26, 1992 | Danielle | Tropical storm, 45 mph | 56 mi |
Source: NOAA National Hurricane Center best-track records (HURDAT2), 1851 to 2025 for the Atlantic and 1949 to 2025 for the eastern Pacific. A storm counts if its track passed within 65 miles of the county's center while it was a tropical storm or hurricane. Strength is the storm's top sustained wind at that point, not the wind measured in the county. Older storms over the open sea were sometimes missed.
Flood insurance in Delaware County
Check your address flood zone ›National Flood Insurance Program (NFIP) records only; private flood policies are not included. Home counts as of Aug 3, 2026. Since 2021 NFIP prices each home separately under Risk Rating 2.0, so your price depends on the building, not the county. Ask an agent for a quote.
Homes in Delaware County
Older homes and mobile homes usually suffer more damage in storms, floods and earthquakes, and can cost more to insure. If you are buying, ask about roof age, foundation bolting and any retrofits. Source: US Census Bureau, American Community Survey 2020 to 2024 5-year estimates; 229,715 housing units.
Compare in Pennsylvania
All 67 ›| Largest counties | Overall risk | Top hazard |
|---|---|---|
| Philadelphia County | Inland flooding | |
| Allegheny County | Inland flooding | |
| Montgomery County | Inland flooding | |
| Bucks County | Inland flooding | |
| Delaware County | Inland flooding | |
| Lancaster County | Inland flooding | |
| Chester County | Inland flooding | |
| York County | Inland flooding |
Neighboring counties
| County | Overall risk | Declarations |
|---|---|---|
| Philadelphia County | 23 | |
| Montgomery County | 27 | |
| New Castle County, DE | 15 | |
| Chester County | 24 | |
| Gloucester County, NJ | 25 |
Cities in Delaware County
Common questions about Delaware County
What is the biggest natural hazard in Delaware County?
Inland flooding has the highest expected yearly losses in Delaware County, about $73.9 million a year in FEMA's estimate. Earthquake is second at $13.3 million.
How many federal disasters has Delaware County had?
Delaware County has been included in 22 federal disaster or emergency declarations for natural events since 1965, including 15 major disasters. The most recent was Remnants of Hurricane Ida in September 2021.
Is Delaware County a high-risk place to live?
Its overall rating is Relatively Moderate, 7th highest of 67 in Pennsylvania. A county rating covers the whole area. Risk at one address can be much higher or lower, so check the FEMA flood map and ask about the home's history.
Do I need flood insurance in Delaware County?
Standard home insurance does not cover flooding. About 1 in 143 homes in Delaware County has federal flood insurance. Lenders require it in mapped high-risk zones, but many flood claims come from outside those zones.
How many tornadoes has Delaware County had?
NOAA records list 5 tornadoes in Delaware County since 1950. The strongest was an F2 tornado on June 29, 1973. The weather service has also logged 63 hail reports and 209 floods here.
How many hurricanes have hit Delaware County?
NOAA's hurricane records show 2 hurricanes and 18 tropical storms passing within 65 miles of the center of Delaware County. The strongest was an unnamed hurricane in 1878, with winds near 90 mph.
Sources: FEMA National Risk Index (December 2025), OpenFEMA Disaster Declarations Summaries, and NFIP policy and claims data. Hazard Compass is independent and not affiliated with FEMA. These figures describe the whole county, not a single property, and are not insurance or safety advice. Report a problem.