Jefferson County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
Very LowComposite Risk Score
National percentile: 27th
Jefferson County faces very low composite natural disaster risk (NRI Risk Index score 27.1, 27th national percentile), driven primarily by drought and heat wave exposure. Expected annual loss across all 18 hazard types is $8M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Jefferson County carries a very low composite natural disaster risk, with a National Risk Index score of 27.1 out of 100 — placing it in the 27th 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.
Most of Jefferson County's expected losses come from drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $900K in expected annual loss and about 13.63 events per year; heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Medium risk — $1M in expected annual loss and about 8.89 events per year; and hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $592K in expected annual loss and about 4.00 events per year. Across all hazards, FEMA estimates $8M in expected annual loss for a population of 16K.
Beyond physical exposure, Jefferson County has a high social vulnerability rating (how susceptible the population is to harm) and a medium community resilience rating (its capacity to prepare for and recover from disasters). That combination — a more vulnerable population with limited resilience — can amplify the human cost of any given event.
The county's disaster history tells the same story: Jefferson County has received 12 federal disaster declarations since 1965, including 6 for flood events and 2 for biological events. The most recent was Covid-19 Pandemic (biological), declared in March 2020.
Among 99 Iowa counties, Jefferson County ranks #73 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | Medium | 13.63 / yr | $900K |
| Heat Wave | Medium | 8.89 / yr | $1M |
| Hail | Medium | 4.00 / yr | $592K |
| Lightning | Medium | 44.91 / yr | $380K |
| Strong Wind | Medium | 5.18 / yr | $613K |
| Landslide | Very Low | 0.14 / yr | $2K |
| Wildfire | Very Low | 0.00 / yr | $52K |
| Tornado | Low | 0.32 / yr | $1M |
| Winter Weather | Low | 12.16 / yr | $40K |
| Ice Storm | Low | 0.36 / yr | $43K |
| Earthquake | Very Low | 0.00 / yr | $114K |
| Cold Wave | Low | 5.32 / yr | $261K |
| Riverine Flood | Very Low | 0.68 / yr | $2M |
| Hurricane | Very Low | 0.01 / yr | $3K |
| 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
Jefferson County has received 12 federal disaster declarations since 1965, most recently Covid-19 Pandemic in March 2020. Most frequent causes: Flood (6), Biological (2), Severe Storm (2).
| Declared | Type | Disaster |
|---|---|---|
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2015 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| May 2013 | Flood | Severe Storms, Straight-Line Winds, and Flooding |
| January 2008 | Severe Ice Storm | Severe Winter Storm |
| March 2007 | Severe Storm | Severe Winter Storms |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| July 1998 | Flood | Severe Storms, Tornadoes and Flooding |
| July 1993 | Flood | Severe Storms & Flooding |
| May 1973 | Flood | Severe Storms & Flooding |
Showing the 10 most recent of 12 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Jefferson County?
Jefferson County has a composite FEMA National Risk Index score of 27.1 out of 100, placing it in the Very Low category and the 27th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Jefferson County?
The three highest-rated hazards are Drought (Medium, $900K EAL), Heat Wave (Medium, $1M EAL), Hail (Medium, $592K EAL). These account for most of the county's expected annual losses.
How does Jefferson County compare to other Iowa counties?
Jefferson County ranks #73 of 99 Iowa counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Jefferson County had?
FEMA records 12 federal disaster declarations for Jefferson County since 1965, most often 6 for flood events and 2 for biological events. The most recent was Covid-19 Pandemic, declared in March 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. Jefferson County's $8M EAL is a statistical average, not a guarantee for any specific year or address.