Delaware tornado risk
New Castle County has the highest tornado risk in Delaware, scoring 88.1 out of 100 — rated "Relatively Moderate" by FEMA's National Risk Index.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | New Castle County | 88.1 | Relatively Moderate | 4 |
| 2 | Kent County | 68.6 | Relatively Moderate | 5 |
| 3 | Sussex County | 63.4 | Relatively Low | 9 |
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.
Tornado risk nationally:
Other hazard risks in Delaware:
Frequently asked questions
What is the highest tornado risk county in Delaware?
New Castle County, DE has the highest tornado risk in Delaware, with a FEMA National Risk Index score of 88.1 out of 100 (rated "Relatively Moderate").
What causes tornado risk in Delaware?
Tornado risk concentrates in the central and southern plains ("Tornado Alley") and the Southeast ("Dixie Alley"), where atmospheric conditions favor supercell thunderstorm development. The highest scores often belong to counties with significant mobile home and manufactured housing stock, which carries disproportionate tornado mortality risk.