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

Polk County Disaster Risk

Polk County, Iowa

FEMA Risk Rating

Relatively Moderate

National Percentile

92th

of 3,144 counties

State Rank

#1

of 99 (1 = highest risk)

Flood Risk

92th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Moderate

Higher than 92% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Relatively Low

Higher than 58% of US counties

Tornado

Tornado and severe thunderstorm risk

Relatively High

Higher than 98% of US counties

Earthquake

Seismic activity and ground shaking risk

Relatively Low

Higher than 67% of US counties

Hurricane

Tropical cyclone and hurricane risk

Very Low

Higher than 27% of US counties

Risk Overview

About Natural Disaster Risk in Polk County, Iowa

Polk County faces the nation's significant hazard exposure

At 91.98, Polk County's composite risk score ranks among America's highest for disaster exposure, earning a Relatively Moderate rating well above the national average. This reflects concerning levels across multiple hazard types, particularly tornadoes and flooding.

Iowa's highest-risk county by composite score

Polk County's 91.98 score dwarfs Iowa's state average of 39.68, making it by far the riskiest county in the state. Elevated tornado (98.12), flood (92.14), and earthquake (66.76) risks create a layered hazard environment unmatched elsewhere in Iowa.

Polk faces dramatically higher risk than peers

Neighboring Pottawattamie County (80.44) and Poweshiek County (31.27) both carry substantially lower risk than Polk County. Polk's position as Iowa's urban center (Des Moines) exposes more people and infrastructure to its concentrated hazard profile.

Tornadoes, floods, and earthquakes pose serious threats

Tornado risk (98.12), flood risk (92.14), and earthquake risk (66.76) are all dangerously elevated in Polk County, with tornado exposure nearly maxed on the hazard scale. These overlapping threats create a complex risk environment that demands serious preparedness planning.

Comprehensive insurance is essential for Polk County

Polk County residents must maintain robust homeowners insurance covering tornadoes, hail, wind, and flood damage—with separate flood insurance from the National Flood Insurance Program if applicable. Establish a family safety plan with multiple shelter options and keep emergency supplies accessible.

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

Preparedness Guide

What to Prepare for in Polk County

Top Hazards by Exposure

  1. #1
    TornadoPrepare
    98th percentile
  2. #2
    FloodPrepare
    92th percentile
  3. #3
    EarthquakePrepare
    67th percentile

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

Risk Advisory: Polk County

Risk Verdict

With a composite score at the 92th percentile, Polk County sits above the national median for natural hazard exposure. Proactive preparedness — not reactive response — is key to managing life in one of the country's higher-risk counties; Polk County residents should plan accordingly.

Hazard Breakdown

Tornado risk is Polk County's dominant natural hazard, ranked at the 98th percentile nationally under FEMA's National Risk Index. Flood ranks second at the 92th percentile nationally. Additional tracked hazards include earthquake (67th percentile), wildfire (58th percentile), hurricane (27th percentile).

Preparedness Context

At the 98th percentile nationally for tornado risk, Polk County households benefit most from a reliable alert system — a NOAA weather radio that activates during overnight hours when residents may not be checking smartphone alerts. Alongside tornado exposure, flood at the 92th percentile nationally means Polk County households face multi-hazard severe-weather seasons that benefit from a single integrated emergency plan covering both threats. For Polk County households, a pre-decided family shelter plan — who goes where, how children are retrieved from school during a warning, and a neighborhood meet-up point if phones fail — provides real protection that no supply kit alone can replicate.

Regional Context

At 52.3 points above the Iowa state average, Polk County carries meaningfully higher natural disaster exposure than a typical Iowa county.

Is your household prepared for Polk 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 Polk County, IA?
Polk County has a FEMA National Risk Index rating of Relatively Moderate, placing it in the 92th 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 Polk County?
Polk County is evaluated for five major natural hazard types: tornado (98th percentile), flooding (92th percentile), earthquake (67th percentile), wildfire (58th percentile), hurricane (27th percentile). The highest-risk hazard is tornado 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 Polk County risk compare to the Iowa average?
Polk County's composite risk percentile is 92th, compared to the Iowa state average of 40th percentile. The state's overall risk rating is Very Low. This means Polk County faces higher natural disaster risk than the typical county in Iowa.
Is Polk County at risk for tornado?
Yes, Polk County's tornado risk is at the 98th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Polk County is at the 92th 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 Polk County higher risk than average?
Polk County's composite risk score of 92th percentile is above the Iowa state average of 40th percentile. This elevated risk is driven by tornado exposure (98th percentile), along with flooding and earthquake and wildfire risk. 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.