Plymouth County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
LowComposite Risk Score
National percentile: 49th
Plymouth County faces low composite natural disaster risk (NRI Risk Index score 49.2, 49th national percentile), driven primarily by hail and drought exposure. Expected annual loss across all 18 hazard types is $18M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Plymouth County carries a low composite natural disaster risk, with a National Risk Index score of 49.2 out of 100 — placing it in the 49th 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 Plymouth County's expected losses come from hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $3M in expected annual loss and about 6.23 events per year; drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $2M in expected annual loss and about 27.77 events per year; and landslide (downhill movement of rock, soil, and debris on unstable slopes) at Low risk — $20K in expected annual loss and about 0.18 events per year. Across all hazards, FEMA estimates $18M in expected annual loss for a population of 26K.
Beyond physical exposure, Plymouth County has a low 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: Plymouth County has received 16 federal disaster declarations since 1965, including 6 for flood events and 4 for severe storm events. The most recent was Severe Storms, Flooding, Straight-Line Winds, and Tornadoes (severe storm), declared in June 2024.
Among 99 Iowa counties, Plymouth County ranks #29 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hail | Medium | 6.23 / yr | $3M |
| Drought | Medium | 27.77 / yr | $2M |
| Landslide | Low | 0.18 / yr | $20K |
| Tornado | Medium | 0.74 / yr | $4M |
| Winter Weather | Medium | 15.26 / yr | $192K |
| Wildfire | Low | 0.00 / yr | $200K |
| Ice Storm | Medium | 1.01 / yr | $251K |
| Cold Wave | Low | 6.58 / yr | $1M |
| Riverine Flood | Low | 3.36 / yr | $6M |
| Strong Wind | Low | 4.24 / yr | $499K |
| Heat Wave | Low | 6.26 / yr | $278K |
| Lightning | Low | 40.11 / yr | $162K |
| Earthquake | Very Low | 0.00 / yr | $17K |
| 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
Plymouth 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: Flood (6), Severe Storm (4), 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 |
| July 2014 | Flood | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| July 2013 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| February 2010 | Severe Storm | Severe Winter Storms and Snowstorm |
| March 2007 | Snowstorm | Snow |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| August 1996 | Severe Storm | Severe Storms, 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 Plymouth County?
Plymouth County has a composite FEMA National Risk Index score of 49.2 out of 100, placing it in the Low category and the 49th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Plymouth County?
The three highest-rated hazards are Hail (Medium, $3M EAL), Drought (Medium, $2M EAL), Landslide (Low, $20K EAL). These account for most of the county's expected annual losses.
How does Plymouth County compare to other Iowa counties?
Plymouth County ranks #29 of 99 Iowa counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Plymouth County had?
FEMA records 16 federal disaster declarations for Plymouth County since 1965, most often 6 for flood events and 4 for severe storm 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. Plymouth County's $18M EAL is a statistical average, not a guarantee for any specific year or address.