Philadelphia County, Pennsylvania: Natural Disaster Risk and History
Philadelphia County, Pennsylvania has a Very High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 99.6 out of 100, higher than about 99% of US counties, with heat waves, cold waves and winter storms scoring highest of its 18 hazards and $667 million a year in expected losses.
OpenFEMA lists 23 federal disaster declarations that included Philadelphia County since 1965, not counting 2 for COVID-19; the latest is DR-4618-PA (Remnants of Hurricane Ida, declared 10 September 2021). NOAA's Storm Prediction Center recorded 10 tornadoes touching Philadelphia County from 1950 to 2025.
Live weather alerts for Pennsylvania All official warnings Latest FEMA declarations
Population 1,602,305 Buildings worth $292 billion Area 144 sq mi Risk rank in Pennsylvania 1 of 67 FIPS 42101
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Heat wave | Very High | 100.0 | $256 million | about 11 a year | 125 |
| Cold wave | Very High | 99.8 | $57 million | about once every 1.3 years | 15 |
| Winter weather | Very High | 99.8 | $1.9 million | about 11 a year | 200 |
| Inland flooding | Very High | 99.6 | $266 million | about 5.8 a year | 163 |
| Tornado | Relatively High | 98.7 | $21 million | about once every 14 years | 8 |
| Earthquake | Relatively High | 98.3 | $42 million | about once every 617 years | — |
| Strong wind | Relatively High | 97.9 | $3.5 million | about 7 a year | 268 |
| Lightning | Relatively High | 96.2 | $1.5 million | about 36 a year | 635,013 strikes |
| Hail | Relatively High | 95.1 | $2.1 million | about 2.5 a year | 95 |
| Hurricane | Relatively High | 94.3 | $12 million | about once every 11 years | 16 |
| Ice storm | Relatively High | 94.2 | $988,753 | about 1.4 a year | 97 |
| Coastal flooding | Relatively High | 85.4 | $2.8 million | about 3.7 a year | — |
| Landslide | Relatively Low | 76.3 | $7,168 | about once every 17 years | — |
| Wildfire | Very Low | 28.7 | $8,805 | rarer than once in 1,000 years | — |
| Drought | Very Low | 21.7 | $4,120 | about 5.8 a year | 161 |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Insufficient Data | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 23
Most common: Hurricane 8, Flood 5, Snowstorm 4, Severe Storm 4.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 1 | Drought |
| 1970s | 2 | Flood ×2 |
| 1990s | 5 | Snowstorm ×2, Hurricane, Flood, Severe Storm |
| 2000s | 5 | Severe Storm ×3, Hurricane ×2 |
| 2010s | 9 | Hurricane ×4, Snowstorm ×2, Flood ×2, Severe Ice Storm |
| 2020s | 1 | Hurricane |
The last 10
Widest declarations that included Philadelphia County
- Hurricane Sandy (2012, EM-3356-PA): 67 Pennsylvania counties designated.
- Hurricane Katrina (2005, EM-3235-PA): 67 Pennsylvania counties designated.
- Tropical Depression Ivan (2004, DR-1557-PA): 67 Pennsylvania counties designated.
Named storms in its declarations: Hurricane Ida (2021), Hurricane Sandy (2013), Hurricane Sandy (2012), Tropical Storm Lee (2011), Hurricane Irene (2011), Hurricane Katrina (2005), Tropical Depression Ivan (2004), Tropical Depression Frances (2004), Hurricane Floyd (1999), Tropical Storm Agnes (1972).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Pennsylvania also had 5 statewide declarations with no county list.
Tornado record since 1950 10
| Tornadoes touching the county | 10 |
|---|---|
| Strongest-rated | (E)F3 ×1 |
| Peak month | July (4) |
| Deadliest | 18 Jan 1999, F0, 0.2 mi path, 0 killed, 18 injured |
| Longest path | 4 Aug 2020, EF2, 20.8 mi path, 0 killed, 18 injured |
| Most recent | 29 Jul 2021, EF3, 3.4 mi path |
| Deaths / injuries on those paths | 0 / 39 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 3 | 3 | 3 | 1 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 1 | 0 | 1 | 1 | 3 | 0 | 1 | 3 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Philadelphia County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Philadelphia County (this page) | — | Very High | 99.6 | Heat wave |
| Delaware County | 25 km | Relatively Moderate | 92.9 | Winter weather |
| Camden County, NJ | 27 km | Relatively Moderate | 93.2 | Winter weather |
| Montgomery County | 30 km | Relatively High | 96.8 | Winter weather |
| Gloucester County, NJ | 33 km | Relatively Moderate | 86.6 | Strong wind |
| Bucks County | 37 km | Relatively High | 94.8 | Ice storm |
Nearest by distance between county centres. Every county in Pennsylvania, ranked.
Vulnerability and resilience
| Social vulnerability | Very High 88.1 |
|---|---|
| Community resilience | Relatively Moderate 48.5 |
| Community risk factor | 1.54 |
| Expected annual loss, all hazards | $667 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Philadelphia County's main hazards
- Right now: National Weather Service alerts for Pennsylvania · all official warnings on Global Incident Tracker.
- Heat wave: Heatstroke warning signs
- Cold wave: Carbon monoxide in winter · Power outages now
- Winter weather: Power outages now · Carbon monoxide in winter
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets 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).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. 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).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Philadelphia County
What natural disasters is Philadelphia County, Pennsylvania most at risk from?
Philadelphia County, Pennsylvania has a Very High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 99.6 out of 100, higher than about 99% of US counties, with heat waves, cold waves and winter storms scoring highest of its 18 hazards and $667 million a year in expected losses.
How many federal disaster declarations has Philadelphia County had?
OpenFEMA lists 23 federal disaster declarations that included Philadelphia County since 1965, not counting 2 for COVID-19; the latest is DR-4618-PA (Remnants of Hurricane Ida, declared 10 September 2021). Another 5 Pennsylvania declarations were made statewide without a county list.
How many tornadoes have hit Philadelphia County?
NOAA's Storm Prediction Center recorded 10 tornadoes touching Philadelphia County from 1950 to 2025. The deadliest: 18 Jan 1999, F0, 0.2 mi path, 0 killed, 18 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.