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

Dewey County Disaster Risk

Dewey County, South Dakota

FEMA Risk Rating

Relatively Low

National Percentile

79th

of 3,144 counties

State Rank

#2

of 66 (1 = highest risk)

Flood Risk

17th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Very Low

Higher than 17% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Moderate

Higher than 83% of US counties

Tornado

Tornado and severe thunderstorm risk

Very Low

Higher than 24% of US counties

Earthquake

Seismic activity and ground shaking risk

Very Low

Higher than 12% of US counties

Risk Overview

About Natural Disaster Risk in Dewey County, South Dakota

Dewey County faces elevated wildfire risk

Dewey County's composite risk score of 78.72 substantially exceeds South Dakota's 26.84 state average, ranking it among the state's most hazard-exposed counties nationally. Despite a "Relatively Low" rating, this represents South Dakota's third-highest composite vulnerability.

Highest-risk county in South Dakota

Dewey County ranks first among South Dakota's 66 counties for overall natural disaster risk, with its 78.72 score dramatically surpassing statewide average. This county faces exposure levels three times the state median.

Dramatically riskier than surrounding areas

Dewey County's 78.72 risk score vastly exceeds those of neighboring Faulk County (7.95), Edmunds County (6.97), and Day County (27.64), making it an isolated high-risk zone. Fall River County to the south (30.92) remains significantly less vulnerable.

Wildfire dominates Dewey County hazards

Wildfire risk reaches 82.98 in Dewey County—the highest in the state—making it by far the county's most pressing natural disaster threat. Tornado risk of 24.40 and flood risk of 17.37 are minimal by comparison, but wildfire exposure demands immediate attention.

Wildfire insurance essential here

Dewey County residents must secure comprehensive wildfire coverage as a non-negotiable priority given the county's 82.98 wildfire risk score. Implement defensible space around your home immediately—remove dead trees, thin vegetation, and clear roof gutters—as these actions reduce loss severity more than any insurance policy.

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

Preparedness Guide

What to Prepare for in Dewey County

Top Hazards by Exposure

  1. #1
    WildfirePrepare
    83th percentile
  2. #2
    TornadoPrepare
    24th percentile
  3. #3
    FloodPrepare
    17th percentile

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

Risk Advisory: Dewey County

Risk Verdict

Dewey County ranks at the 79th percentile nationally for natural disaster risk — below the median for U.S. counties. Comprehensive household preparedness — including reviewing insurance, maintaining emergency supplies, and knowing evacuation routes — is strongly recommended.

Hazard Breakdown

Wildfire risk is Dewey County's dominant natural hazard, ranked at the 83th percentile nationally under FEMA's National Risk Index. Tornado ranks second at the 24th percentile nationally. Additional tracked hazards include flood (17th percentile), earthquake (12th percentile).

Preparedness Context

Dewey County's dominant hazard is wildfire, ranked at the 83th percentile nationally. Maintaining at least 30 feet of lean, clean vegetation around structures in Dewey County and keeping gutters clear of debris significantly reduces ignition risk from wind-driven embers. Alongside wildfire, tornado at the 24th percentile nationally means a multi-season preparedness mindset — fire season and flood or storm season often require different household plans. Dewey County's households benefit from reviewing homeowners insurance before fire season, specifically whether the policy covers replacement cost rather than actual cash value, and whether it includes additional living expenses if displacement is required.

Regional Context

Compared to other South Dakota counties, Dewey County runs 51.9 composite risk points higher than the state mean — reflecting above-average hazard concentration in this area.

Is your household prepared for Dewey 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 Dewey County, SD?
Dewey County has a FEMA National Risk Index rating of Relatively Low, placing it in the 79th 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 Dewey County?
Dewey County is evaluated for five major natural hazard types: wildfire (83th percentile), tornado (24th percentile), flooding (17th percentile), earthquake (12th percentile). The highest-risk hazard is wildfire at the 83th 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 Dewey County risk compare to the South Dakota average?
Dewey County's composite risk percentile is 79th, compared to the South Dakota state average of 27th percentile. The state's overall risk rating is Very Low. This means Dewey County faces higher natural disaster risk than the typical county in South Dakota.
Is Dewey County at risk for wildfire?
Yes, Dewey County's wildfire risk is at the 83th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Dewey County is at the 17th percentile.
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 Dewey County higher risk than average?
Dewey County's composite risk score of 79th percentile is above the South Dakota state average of 27th percentile. This elevated risk is driven by wildfire exposure (83th percentile). Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.
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.