Delaware inland flooding risk
New Castle County has the highest inland flooding risk in Delaware, scoring 97.6 out of 100 — rated "Relatively High" by FEMA's National Risk Index. Recorded inland flooding events across Delaware have decreased 66% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | New Castle County | 97.6 | Relatively High | 88 |
| 2 | Sussex County | 92.8 | Relatively Moderate | 47 |
| 3 | Kent County | 82.9 | Relatively Moderate | 18 |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Inland Flooding risk nationally:
Other hazard risks in Delaware:
Frequently asked questions
What is the highest inland flooding risk county in Delaware?
New Castle County, DE has the highest inland flooding risk in Delaware, with a FEMA National Risk Index score of 97.6 out of 100 (rated "Relatively High").
What causes inland flooding risk in Delaware?
Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.