Lyon County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
Very LowComposite Risk Score
National percentile: 19th
Lyon County faces very low composite natural disaster risk (NRI Risk Index score 19.2, 19th national percentile), driven primarily by hail and drought exposure. Expected annual loss across all 18 hazard types is $11M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Lyon County carries a very low composite natural disaster risk, with a National Risk Index score of 19.2 out of 100 — placing it in the 19th national percentile and among the lowest-risk counties in the country. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $3M in expected annual loss and about 6.13 events per year; drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $906K in expected annual loss and about 19.94 events per year; and winter weather (heavy snow, blizzards, and hazardous winter conditions) at Medium risk — $209K in expected annual loss and about 18.42 events per year. Across all hazards, FEMA estimates $11M in expected annual loss for a population of 12K.
Beyond physical exposure, Lyon County has a very low social vulnerability rating (how susceptible the population is to harm) and a 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.
History supports the rating: Lyon County has received 16 federal disaster declarations since 1965, including 6 for severe storm events and 6 for flood events. The most recent was Severe Storms, Flooding, Straight-Line Winds, and Tornadoes (severe storm), declared in June 2024.
Among 99 Iowa counties, Lyon County ranks #86 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hail | Medium | 6.13 / yr | $3M |
| Drought | Medium | 19.94 / yr | $906K |
| Winter Weather | Medium | 18.42 / yr | $209K |
| Ice Storm | Medium | 1.20 / yr | $303K |
| Tornado | Low | 0.50 / yr | $2M |
| Cold Wave | Low | 8.58 / yr | $1M |
| Landslide | Very Low | 0.07 / yr | $615 |
| Heat Wave | Very Low | 5.11 / yr | $206K |
| Wildfire | Very Low | 0.00 / yr | $20K |
| Riverine Flood | Very Low | 2.36 / yr | $4M |
| Strong Wind | Low | 4.23 / yr | $248K |
| Lightning | Very Low | 38.95 / yr | $47K |
| Earthquake | Very Low | 0.00 / yr | $11K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Lyon County has received 16 federal disaster declarations since 1965, most recently Severe Storms, Flooding, Straight-Line Winds, and Tornadoes in June 2024. Most frequent causes: Severe Storm (6), Flood (6), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| June 2024 | Severe Storm | Severe Storms, Flooding, Straight-Line Winds, and Tornadoes |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| March 2019 | Flood | Severe Storms and Flooding |
| August 2018 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| July 2014 | Flood | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| July 2013 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| May 2013 | Severe Storm | Severe Winter Storm |
| July 2010 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| May 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
Showing the 10 most recent of 16 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Lyon County?
Lyon County has a composite FEMA National Risk Index score of 19.2 out of 100, placing it in the Very Low category and the 19th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Lyon County?
The three highest-rated hazards are Hail (Medium, $3M EAL), Drought (Medium, $906K EAL), Winter Weather (Medium, $209K EAL). These account for most of the county's expected annual losses.
How does Lyon County compare to other Iowa counties?
Lyon County ranks #86 of 99 Iowa counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Lyon County had?
FEMA records 16 federal disaster declarations for Lyon County since 1965, most often 6 for severe storm events and 6 for flood events. The most recent was Severe Storms, Flooding, Straight-Line Winds, and Tornadoes, declared in June 2024.
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. Lyon County's $11M EAL is a statistical average, not a guarantee for any specific year or address.