Washington County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
LowComposite Risk Score
National percentile: 44th
Washington County faces low composite natural disaster risk (NRI Risk Index score 44.2, 44th national percentile), driven primarily by strong wind and hail exposure. Expected annual loss across all 18 hazard types is $14M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Washington County at low composite risk, with a National Risk Index score of 44.2 out of 100 — placing it in the 44th national percentile and below the national average for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Washington County's expected losses come from strong wind (damaging straight-line winds outside of tornadoes and hurricanes) at High risk — $2M in expected annual loss and about 6.20 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $1M in expected annual loss and about 4.44 events per year; and drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $869K in expected annual loss and about 8.45 events per year. Across all hazards, FEMA estimates $14M in expected annual loss for a population of 23K.
Beyond physical exposure, Washington County has a medium social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The federal record bears this out: Washington County has received 15 federal disaster declarations since 1965, including 7 for severe storm events and 4 for flood events. The most recent was Severe Storms (severe storm), declared in August 2020.
Among 99 Iowa counties, Washington County ranks #33 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Strong Wind | High | 6.20 / yr | $2M |
| Hail | Medium | 4.44 / yr | $1M |
| Drought | Medium | 8.45 / yr | $869K |
| Heat Wave | Low | 8.26 / yr | $716K |
| Landslide | Very Low | 0.14 / yr | $3K |
| Tornado | Low | 0.49 / yr | $2M |
| Wildfire | Very Low | 0.00 / yr | $62K |
| Winter Weather | Low | 13.58 / yr | $71K |
| Lightning | Low | 44.40 / yr | $220K |
| Riverine Flood | Low | 1.68 / yr | $6M |
| Ice Storm | Low | 0.35 / yr | $74K |
| Cold Wave | Low | 6.05 / yr | $800K |
| Earthquake | Very Low | 0.00 / yr | $114K |
| Hurricane | Very Low | 0.01 / yr | $6K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Washington County has received 15 federal disaster declarations since 1965, most recently Severe Storms in August 2020. Most frequent causes: Severe Storm (7), Flood (4), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| August 2020 | Severe Storm | Severe Storms |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| August 2014 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| July 2010 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| May 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| January 2008 | Severe Ice Storm | Severe Winter Storm |
| March 2007 | Severe Storm | Severe Winter Storms |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| May 2004 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
Showing the 10 most recent of 15 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Washington County?
Washington County has a composite FEMA National Risk Index score of 44.2 out of 100, placing it in the Low category and the 44th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Washington County?
The three highest-rated hazards are Strong Wind (High, $2M EAL), Hail (Medium, $1M EAL), Drought (Medium, $869K EAL). These account for most of the county's expected annual losses.
How does Washington County compare to other Iowa counties?
Washington County ranks #33 of 99 Iowa counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Washington County had?
FEMA records 15 federal disaster declarations for Washington County since 1965, most often 7 for severe storm events and 4 for flood events. The most recent was Severe Storms, declared in August 2020.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Washington County's $14M EAL is a statistical average, not a guarantee for any specific year or address.