riskbycounty
FEMA NRI 1.19.0Updated Nov 2023 · Coverage 2014–2023Methodology

New Castle County Disaster Risk

New Castle County, Delaware

FEMA Risk Rating

Relatively High

National Percentile

95th

of 3,144 counties

State Rank

#1

of 3 (1 = highest risk)

Flood Risk

98th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Relatively High

Higher than 98% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Relatively Low

Higher than 61% of US counties

Tornado

Tornado and severe thunderstorm risk

Moderate

Higher than 88% of US counties

Earthquake

Seismic activity and ground shaking risk

Moderate

Higher than 93% of US counties

Hurricane

Tropical cyclone and hurricane risk

Moderate

Higher than 88% of US counties

Risk Overview

About Natural Disaster Risk in New Castle County, Delaware

New Castle County faces high risk

New Castle County's composite risk score of 95.29 ranks well above the national average, earning a "Relatively High" rating for natural disaster exposure. This places the county among America's higher-risk areas, driven by exceptional flood and earthquake vulnerabilities.

Delaware's riskiest county

New Castle County tops Delaware's hazard rankings with a composite score of 95.29, significantly higher than the state average of 91.32. The county's flood risk (97.58) and tornado risk (88.14) push it well above statewide norms, making it the state's most disaster-prone area.

Notably riskier than Sussex and Kent

New Castle County's 95.29 score outpaces Sussex County (94.15) and substantially exceeds Kent County (84.51), making it Delaware's hazard hotspot. The difference is most pronounced in flood risk, where New Castle scores 97.58—among the highest in the nation for this specific threat.

Floods and tornadoes dominate exposure

Flood risk (97.58) and earthquake risk (92.88) represent New Castle County's most severe hazards, with tornado risk (88.14) also ranking dangerously high. Together, these three threats create a complex disaster landscape requiring multi-layered protection strategies.

Comprehensive coverage is essential

New Castle County residents should prioritize flood insurance immediately—the 97.58 flood risk score means many properties face genuine exposure that standard policies won't cover. Additionally, review your homeowners policy for adequate tornado/wind coverage and consider a separate earthquake policy given the 92.88 seismic risk score.

Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor

Preparedness Guide

What to Prepare for in New Castle County

Top Hazards by Exposure

  1. #1
    FloodPrepare
    98th percentile
  2. #2
    EarthquakePrepare
    93th percentile
  3. #3
    HurricanePrepare
    88th percentile

Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)

Local Resources

Risk Advisory: New Castle County

Risk Verdict

New Castle County carries an elevated natural disaster risk burden, scoring at the 95th percentile nationally under FEMA's risk model. This risk level calls for more than general awareness: insurance coverage review, a family communication plan, and a prepared go-bag are practical priorities.

Hazard Breakdown

Flood risk is New Castle County's dominant natural hazard, ranked at the 98th percentile nationally under FEMA's National Risk Index. Earthquake ranks second at the 93th percentile nationally. Additional tracked hazards include hurricane (88th percentile), tornado (88th percentile), wildfire (61th percentile).

Preparedness Context

New Castle County's top natural hazard is flood risk, ranked at the 98th percentile nationally. Homeowners here should confirm whether they are in a FEMA-designated flood zone and check if standard homeowners insurance covers flood damage — it typically does not. The county's second-ranked hazard, earthquake at the 93th percentile nationally, means New Castle County residents face compounding risks from multiple natural hazard types during peak seasons. For most New Castle County households, the highest-return preparedness step is storing critical documents in digital cloud backup combined with a pre-designated family meeting point if communication is disrupted.

Regional Context

At just 4.0 composite points from the Delaware average, New Castle County's natural disaster risk is closely in line with its in-state peers.

Is your household prepared for New Castle County's hazards?

Review FEMA's county-specific preparedness checklists and emergency planning guides.

FEMA Ready Guide →

Frequently Asked Questions

What is the natural disaster risk in New Castle County, DE?
New Castle County has a FEMA National Risk Index rating of Relatively High, placing it in the 95th 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.
What types of natural hazards affect New Castle County?
New Castle County is evaluated for five major natural hazard types: flooding (98th percentile), earthquake (93th percentile), hurricane (88th percentile), tornado (88th percentile), wildfire (61th percentile). The highest-risk hazard is flooding at the 98th 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.
How does New Castle County risk compare to the Delaware average?
New Castle County's composite risk percentile is 95th, compared to the Delaware state average of 91th percentile. The state's overall risk rating is Relatively Moderate. This means New Castle County faces higher natural disaster risk than the typical county in Delaware.
Is New Castle County at risk for flooding?
Yes, New Castle County's flooding risk is at the 98th percentile nationally. This places it in the top quartile for this hazard type.
How is natural disaster risk measured?
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.
Why is New Castle County higher risk than average?
New Castle County's composite risk score of 95th percentile is above the Delaware state average of 91th percentile. This elevated risk is driven by flooding exposure (98th percentile), along with earthquake and hurricane and tornado and wildfire risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.

Counties with Similar Risk

Sussex County

Delaware

-1.1

Relatively Moderate

94th percentile

Kent County

Delaware

-10.8

Relatively Moderate

85th percentile

By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

Data Source

Risk data sourced from the FEMA National Risk Index (NRI). Risk scores are relative rankings (0–100) across all US counties — not absolute risk measures. Higher scores indicate higher relative risk compared to other counties.

Disclaimer: This data is informational only. It is not financial, insurance, or legal advice. Always consult a qualified professional before making insurance or real estate decisions.

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