Natural disaster risk in Chester County, Pennsylvania
Pennsylvania · population 534,152 · FIPS 42029
Overall: relatively moderate risk
Chester County has a composite risk score of 91.9 out of 100 — higher than 91% of US counties. It ranks 9 of 67 in Pennsylvania (1 = highest risk). Its highest-rated hazards are winter weather, drought, inland (riverine) flooding.
Drought now: No, but abnormally dry (D0)
No drought, but abnormally dry. On the U.S. Drought Monitor map valid 13 October 2026, 0.99% of Chester County is D0 Abnormally Dry and none of it is in drought (D1 to D4). Some of it has been abnormally dry or worse for at least 54 weeks in a row.
Drought in Chester County: the last 52 weeks · droughtmonitor.unl.edu
The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration. Map courtesy of NDMC.
Risk, loss, vulnerability and resilience
| Measure | Rating and score |
|---|---|
| Overall risk Expected annual loss, adjusted for social vulnerability and community resilience. |
Relatively moderate 91.9 |
| Expected annual loss About $172.6 million a year, on average, across all 18 hazards. |
Relatively moderate 95 |
| Social vulnerability Higher means people may find it harder to prepare and recover. |
Very low 10.6 |
| Community resilience Higher means a stronger ability to prepare, adapt and recover. |
Very high 85.2 |
Risk by hazard
FEMA's risk rating for each of 18 natural hazards in Chester County, highest first. "Not applicable" means the hazard is not modelled here.
| Hazard | Risk rating and score |
|---|---|
| Winter weather | Very high 98 |
| Drought | Relatively high 98 |
| Inland (riverine) flooding | Relatively high 94 |
| Strong wind | Relatively high 94 |
| Lightning | Relatively high 91 |
| Ice storm | Relatively high 85 |
| Heat wave | Relatively moderate 95 |
| Earthquake | Relatively moderate 90 |
| Hurricane | Relatively moderate 88 |
| Tornado | Relatively moderate 87 |
| Cold wave | Relatively moderate 84 |
| Landslide | Relatively low 77 |
| Hail | Relatively low 61 |
| Wildfire | Very low 30 |
| Avalanche | Not applicable |
| Coastal flooding | No rating |
| Tsunami | Not applicable |
| Volcanic activity | Not applicable |
FEMA disaster declarations for Chester County
Federal declarations that designated Chester County, since 1 Jan 2024 (the period this site keeps from OpenFEMA). Older declarations are in FEMA's own dataset.
Not since 1 Jan 2024: no FEMA disaster declaration in the records this site read names Chester County.
All FEMA declarations in Pennsylvania, with estimated apply-by dates · Open FEMA deadlines
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). Dataset: Disaster Declarations Summaries - v2.
How to read these ratings
- Ratings run in five steps: very low, relatively low, relatively moderate, relatively high and very high. They compare a county with every other US county; they are not a measure of danger on their own.
- Scores run from 0 to 100 and are national percentiles. The bar shows the score: a score of 80 means a higher value than 80% of US counties.
- Overall risk combines the expected annual loss with social vulnerability and community resilience.
- Expected annual loss is the average yearly loss to buildings, people and agriculture the model expects from all 18 hazards.
- Social vulnerability describes how hard it may be for people to prepare for and recover from a disaster. Higher is worse.
- Community resilience describes a community's ability to prepare, adapt and recover. Higher is better.
- "Not applicable" means FEMA does not model that hazard there (for example, hurricanes far inland).
About this data
Source: FEMA National Risk Index, version 1.20, released December 2025, published by the Federal Emergency Management Agency (US public domain). About the National Risk Index. The index is a model of relative risk built from historical hazard records, what is exposed and community factors. It is not a forecast, it does not describe any single property, and it is not insurance or financial advice. For decisions about a specific address, check FEMA's flood maps and your local emergency management office.
Questions
What is the natural disaster risk in Chester County, Pennsylvania?
FEMA's National Risk Index rates the overall risk in Chester County as relatively moderate, with a score of 91.9 out of 100 (higher than 91% of US counties). That is a comparison with other US counties, not a forecast.
What are the biggest natural hazards in Chester County?
The hazards rated highest for Chester County are winter weather (very high), drought (relatively high), inland (riverine) flooding (relatively high).
What is the flood risk in Chester County?
FEMA rates inland (river and rain) flooding risk in Chester County as relatively high. For a specific property, check the FEMA flood map and your local floodplain office.
Has Chester County had a FEMA disaster declaration?
Not since 1 Jan 2024: no FEMA disaster declaration in the records this site read names Chester County.
Is Chester County in a drought?
No drought, but abnormally dry. On the U.S. Drought Monitor map valid 13 October 2026, 0.99% of Chester County is D0 Abnormally Dry and none of it is in drought (D1 to D4). Some of it has been abnormally dry or worse for at least 54 weeks in a row.
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