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Delaware County, Pennsylvania

Natural disaster risk, federal disaster history and flood insurance facts.

Relatively Moderate overall risk
7th of 67highest risk in Pennsylvania
$135Mexpected losses a year
22federal declarations
1 in 143homes with flood insurance
Photo: U.S. Geological Survey, public domain

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

$73.9 million a yearExpected losses. Damaging events about 5 times a year.
  • 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.

Earthquake

Moderate
$13.3 million a yearExpected losses. Damaging events about once every 620 years.
  • Ask whether an older house is bolted to its foundation.
  • Consider separate earthquake insurance where risk is high.
$12.8 million a yearExpected losses. Damaging events about 11 times a year.
  • Check that cooling works before summer.
  • Know where the nearest cooling center is.
HazardRatingScoreExpected loss a year
Inland floodingHigh94.4
$74M
EarthquakeModerate94.5
$13M
Heat waveHigh97.6
$13M
TornadoHigh92.5
$9M
Cold waveHigh91.5
$9M
HurricaneModerate88.1
$6M
Strong windHigh97.7
$5M
Winter weatherVery High99.2
$2M
LightningHigh95.6
$2M
Ice stormHigh87.0
$750K
Coastal floodingModerate63.6
$730K
DroughtLow54.2
$209K
HailVery Low13.3
$46K
WildfireVery Low27.7
$13K
LandslideVery Low59.4
$3K
AvalancheVery Low11.4
$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

Hurricane7
Flood6
Severe Storm4
Snowstorm3
Drought1
Severe Ice Storm1

Most recent

Sep 10, 2021Remnants of Hurricane IdaMajor disaster
Feb 6, 2014Severe Winter StormEmergency
Oct 29, 2012Hurricane SandyEmergency
Sep 12, 2011Tropical Storm LeeMajor disaster
Sep 8, 2011Remnants of Tropical Storm LeeEmergency
Sep 3, 2011Hurricane IreneMajor disaster
Aug 29, 2011Hurricane IreneEmergency
Apr 16, 2010Severe Winter Storms and SnowstormsMajor disaster
Sep 10, 2005Hurricane KatrinaEmergency
Sep 19, 2004Tropical Depression IvanMajor disaster
Show all 22
Sep 19, 2004Severe Storms and Flooding Associated With Tropical Depression FrancesMajor disaster
Aug 6, 2004Severe Storms and FloodingMajor disaster
Mar 14, 2003SnowEmergency
Sep 18, 1999Hurricane Floyd Major Disaster DeclarationsMajor disaster
Jan 21, 1996Severe Storms and FloodingMajor disaster
Jan 13, 1996Blizzard of 96Major disaster
Mar 10, 1994Severe Winter StormsMajor disaster
Mar 16, 1993Severe Snowfall & Winter StormEmergency
Jul 17, 1973Severe Storms & FloodingMajor disaster
Jun 23, 1972Tropical Storm AgnesMajor disaster
Sep 18, 1971FloodsMajor disaster
Aug 18, 1965Water ShortageMajor disaster

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.

5tornadoes
63hail reports, largest 1.75 inches
341damaging thunderstorm winds
209floods and flash floods

Strongest tornadoes

DateStrengthNearHurt / killed
Jun 29, 1973F2–0 / 0
Oct 31, 2019EF2Glen Mills2 / 0
Sep 27, 1993F1Springfield0 / 0
Jul 15, 1992F1–0 / 0
Aug 22, 2010EF0Trainer0 / 0

Most damaging storms

DateTypeNearDamage
Sep 16, 1999Flash FloodCountywide$15M
Sep 1, 2021Flash FloodEdgemont$15M
Sep 1, 2021Flash FloodBooth Corner$15M
Aug 1, 2004Flash FloodEast Portion$10M
Sep 27, 1993TornadoSpringfield$5M
Oct 1, 2010FloodChadds 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.

2hurricanes
0major hurricanes (Category 3+)
18tropical storms
2020most recent: Isaias

Strongest storms nearby

DateStormStrengthClosest
Oct 23, 1878UnnamedCategory 1, 90 mph64 mi
Sep 16, 1903UnnamedCategory 1, 80 mph64 mi
Aug 28, 2011IreneTropical storm, 70 mph64 mi
Jul 13, 1996BerthaTropical storm, 70 mph46 mi
Aug 4, 2020IsaiasTropical storm, 65 mph52 mi
Aug 28, 1971DoriaTropical storm, 65 mph60 mi

Most recent storms

DateStormStrengthClosest
Aug 4, 2020IsaiasTropical storm, 65 mph52 mi
Jul 10, 2020FayTropical storm, 50 mph64 mi
Aug 28, 2011IreneTropical storm, 70 mph64 mi
Sep 6, 2008HannaTropical storm, 50 mph46 mi
Jul 13, 1996BerthaTropical storm, 70 mph46 mi
Sep 26, 1992DanielleTropical storm, 45 mph56 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 ›
0.7%of homes have federal flood insurance (1,153 policies)
38.6%of homes in mapped high-risk flood zones are insured
$56.7 millionpaid on 3,034 flood claims since 1978
1999costliest year, with $11.6 million paid

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

$332,200median home value (Pennsylvania $254,500, US $332,700)
1957median year homes were built (Pennsylvania 1965, US 1980)
79%of homes built before 1980, before many modern wind, quake and flood building rules
0.3%of homes are mobile homes, which are the least safe in tornadoes and high winds

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 countiesOverall riskTop hazard
Philadelphia CountyVery HighInland flooding
Allegheny CountyHighInland flooding
Montgomery CountyHighInland flooding
Bucks CountyHighInland flooding
Delaware CountyModerateInland flooding
Lancaster CountyHighInland flooding
Chester CountyModerateInland flooding
York CountyModerateInland flooding

Neighboring counties

CountyOverall riskDeclarations
Philadelphia CountyVery High23
Montgomery CountyHigh27
New Castle County, DEHigh15
Chester CountyModerate24
Gloucester County, NJModerate25

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.