Union County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
LowComposite Risk Score
National percentile: 50th
Union County faces low composite natural disaster risk (NRI Risk Index score 49.5, 50th national percentile), driven primarily by drought and cold wave exposure. Expected annual loss across all 18 hazard types is $13M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Union County is low, with a National Risk Index score of 49.5 out of 100 — placing it in the 50th 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.
Risk here concentrates in drought (extended dry periods that stress water supplies and agriculture) at High risk — $2M in expected annual loss and about 6.28 events per year; cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $4M in expected annual loss and about 4.74 events per year; and heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Medium risk — $1M in expected annual loss and about 7.68 events per year. Across all hazards, FEMA estimates $13M in expected annual loss for a population of 12K.
Beyond physical exposure, Union County has a high 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). Higher vulnerability is partly offset by strong community resilience and recovery capacity.
The county's disaster history tells the same story: Union County has received 21 federal disaster declarations since 1969, including 7 for severe storm events and 6 for flood events. The most recent was Severe Storms and Tornadoes (tornado), declared in May 2024.
Among 99 Iowa counties, Union County ranks #28 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | High | 6.28 / yr | $2M |
| Cold Wave | Medium | 4.74 / yr | $4M |
| Heat Wave | Medium | 7.68 / yr | $1M |
| Hail | Medium | 5.88 / yr | $528K |
| Landslide | Low | 0.18 / yr | $3K |
| Tornado | Low | 0.34 / yr | $1M |
| Strong Wind | Medium | 4.87 / yr | $484K |
| Wildfire | Very Low | 0.00 / yr | $37K |
| Winter Weather | Low | 11.89 / yr | $41K |
| Ice Storm | Low | 0.56 / yr | $36K |
| Riverine Flood | Very Low | 1.04 / yr | $3M |
| Earthquake | Very Low | 0.00 / yr | $32K |
| Lightning | Very Low | 45.13 / yr | $52K |
| Hurricane | Very Low | 0.01 / yr | $2K |
| 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
Union County has received 21 federal disaster declarations since 1969, most recently Severe Storms and Tornadoes in May 2024. Most frequent causes: Severe Storm (7), Flood (6), Tornado (2).
| Declared | Type | Disaster |
|---|---|---|
| May 2024 | Tornado | Severe Storms and Tornadoes |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| March 2019 | Flood | Severe Storms and Flooding |
| July 2010 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| March 2010 | Severe Storm | Severe Winter Storm |
| May 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| January 2008 | Severe Ice Storm | Severe Winter Storm |
| September 2007 | Severe Storm | Severe Storms and Flooding |
| May 2007 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
Showing the 10 most recent of 21 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Union County?
Union County has a composite FEMA National Risk Index score of 49.5 out of 100, placing it in the Low category and the 50th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Union County?
The three highest-rated hazards are Drought (High, $2M EAL), Cold Wave (Medium, $4M EAL), Heat Wave (Medium, $1M EAL). These account for most of the county's expected annual losses.
How does Union County compare to other Iowa counties?
Union County ranks #28 of 99 Iowa counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Union County had?
FEMA records 21 federal disaster declarations for Union County since 1969, most often 7 for severe storm events and 6 for flood events. The most recent was Severe Storms and Tornadoes, declared in May 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. Union County's $13M EAL is a statistical average, not a guarantee for any specific year or address.