Johnson County, IA
FEMA National Risk Index scores, disaster declarations & hazard data
Johnson County has experienced 24 federally declared disasters since 1965, most recently Covid-19 in 2020. Its overall natural hazard risk is rated Relatively Moderate — near the middle compared to other US counties.
Johnson County's highest-rated hazards are strong wind, tornado, and hail, with its top risk rated "Very High" by FEMA's National Risk Index. NOAA records 104 storm events in the county over the past decade.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Johnson County has been designated in 24 declarations since 1965, covering 6 disaster types including flood (12), severe storm (7), biological (2).
| Year | Type | Event name |
|---|---|---|
| 2020 | Severe Storm | Severe Storms |
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2014 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, And Flooding |
| 2013 | Severe Storm | Severe Storms, Tornadoes, And Flooding |
| 2013 | Flood | Severe Storms, Straight-Line Winds, And Flooding |
| 2008 | Severe Ice Storm | Severe Winter Storm |
| 2008 | Severe Storm | Severe Storms, Tornadoes, And Flooding |
| 2007 | Severe Storm | Severe Winter Storms |
| 2005 | Hurricane | Hurricane Katrina Evacuation |
Showing the 10 most recent of 24 total declarations since 1965.
Source: FEMA OpenFEMA Disaster Declarations Summaries. A single disaster can produce more than one record per county. Data current through September 2026.
Risk by hazard type
| Hazard | Risk rating | Risk score | Recorded events | Deaths | Prop. damage |
|---|---|---|---|---|---|
| Wildfire | Relatively Low | 64.4 | 0 | 0 | — |
| Inland Flooding | Relatively Moderate | 79.8 | 20 | 0 | $1.5M |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Very Low | 45.1 | — | — | — |
| Heat Wave | Relatively Moderate | 87.5 | 0 | 0 | — |
| Tornado | Relatively High | 98.2 | 13 | 0 | — |
| Hurricane | Very Low | 13.6 | 0 | 0 | — |
| Hail | Relatively High | 95.3 | 86 | 0 | — |
| Strong Wind | Very High | 98.9 | 0 | 0 | — |
| Winter Weather | Relatively High | 87.9 | 0 | 0 | — |
| Ice Storm | Relatively Moderate | 75.7 | — | — | — |
| Cold Wave | Relatively High | 90.3 | — | — | — |
| Lightning | Relatively Moderate | 74.5 | 0 | 0 | — |
| Drought | Relatively Moderate | 81.8 | 0 | 0 | — |
| Landslide | Relatively Low | 79.1 | 0 | 0 | — |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic Activity | Not Applicable | — | — | — | — |
Scores are 0–100 percentiles relative to all US counties — higher means more exposed, not that a disaster is likely this year. Event counts: NOAA Storm Events 2016–2026; earthquake counts from USGS ComCat (M3.0+, 1996–2026). See the methodology page for details.
Community vulnerability
Johnson County ranks in the 39th percentile (Low) for community vulnerability — a measure of how hard disaster impacts tend to hit residents. Higher vulnerability means more displacement, worse health outcomes, and slower recovery after a disaster.
| SVI theme | Percentile | Vulnerability level |
|---|---|---|
| Overall | 39th | Low |
| Socioeconomic status | 34th | Low |
| Household characteristics | 2nd | Very low |
| Racial & ethnic minority status | 58th | Moderate |
| Housing type & transportation | 89th | High |
Source: CDC/ATSDR Social Vulnerability Index 2022. Percentiles compare counties nationally — higher means more vulnerable relative to other counties. See CDC SVI for full methodology.
Future risk outlook
| Wildfire metric | National percentile | Level |
|---|---|---|
| Burn probability | 40th | Relatively Moderate |
| Risk to homes | 38th | Relatively Low |
| Buildings in direct exposure zone | 30.4% | — |
NOAA tracked 104 weather events in this county over 2016–2025: 56 in 2016–20 vs 48 in 2021–25 (-14% — frequency decreasing).
Wildfire: USDA Forest Service Wildfire Risk to Communities (RDS-2020-0016-2) — modeled values, not annual forecasts. See wildfirerisk.org. Inland flood and heat projections pending data availability; coastal sea-level projections are available for select coastal counties below — see the data page.
Nearby counties
Frequently asked questions
What natural hazards pose the greatest risk in Johnson County?
According to the FEMA National Risk Index, the highest-risk hazards in Johnson County, Iowa are strong wind, tornado, and hail. The county's overall natural hazard risk is rated Relatively Moderate — near the middle compared to other US counties.
Has Johnson County received federal disaster declarations?
Yes. Johnson County has received 24 federal disaster declarations since 1965, including declarations in 2020. The most common disaster type on record is flood (12 declarations).
Has Johnson County had any FEMA disaster declarations in 2024, 2025, or 2026?
No federal disaster declarations have been recorded for Johnson County since the start of 2024. Its most recent declaration on record is Covid-19 in 2020.
How does Johnson County's natural hazard risk compare to nearby counties?
Among neighboring counties, Linn County, IA has the highest overall natural hazard risk (Relatively Moderate) and Louisa County, IA has the lowest (Very Low). Johnson County is rated Relatively Moderate overall.
How is Johnson County's composite disaster risk index calculated?
Johnson County's composite disaster risk index — officially FEMA's National Risk Index (NRI) — scores every US county on a 0–100 percentile scale across 18 natural hazard types, factoring in expected annual loss, social vulnerability, and community resilience. Johnson County's composite score of 87 means its overall natural hazard risk is higher than 87% of US counties.