Philadelphia County Disaster Risk

Philadelphia County has a FEMA National Risk Index rating of Very High, placing it in the 100th percentile nationally out of 3,144 counties. This composite score reflects the county's overall exposure to natural hazards including floods, wildfires, tornadoes, earthquakes, and hurricanes, weighted by expected annual loss and social vulnerability.

Philadelphia County is evaluated for five major natural hazard types: flooding (100th percentile), tornado (99th percentile), earthquake (98th percentile), hurricane (94th percentile), wildfire (29th percentile). The highest-risk hazard is flooding at the 100th percentile nationally. These scores are derived from FEMA's National Risk Index, which analyzes expected annual loss, social vulnerability, and community resilience for each hazard type.

Philadelphia County's composite risk percentile is 100th, compared to the Pennsylvania state average of 67th percentile. The state's overall risk rating is Relatively Low. This means Philadelphia County faces higher natural disaster risk than the typical county in Pennsylvania.

Yes, Philadelphia County's flooding risk is at the 100th percentile nationally. This places it in the top quartile for this hazard type.

FEMA's National Risk Index (NRI) calculates risk scores for 18 natural hazard types across all U.S. counties and census tracts. The composite score combines Expected Annual Loss (estimated dollar losses from each hazard), Social Vulnerability (demographic factors affecting disaster impact), and Community Resilience (ability to recover). Percentile scores rank each county against all 3,144 U.S. counties, and risk ratings range from Very Low to Very High.

Philadelphia County's composite risk score of 100th percentile is above the Pennsylvania state average of 67th percentile. This elevated risk is driven by flooding exposure (100th percentile), along with tornado and earthquake and hurricane risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.