Mercer County, IL
FEMA National Risk Index scores, disaster declarations & hazard data
Mercer County has experienced 15 federally declared disasters since 1965, most recently Covid-19 in 2020. Its overall natural hazard risk is rated Very Low — among the lowest-risk counties in the country.
Mercer County's highest-rated hazards are drought, landslide, and ice storm, with its top risk rated "Relatively Moderate" by FEMA's National Risk Index. NOAA records 51 storm events in the county over the past decade. Community vulnerability is relatively low (6th percentile nationally), indicating stronger recovery capacity than most US counties.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Mercer County has been designated in 15 declarations since 1965, covering 6 disaster types including flood (7), snowstorm (3), biological (2).
| Year | Type | Event name |
|---|---|---|
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2019 | Flood | Severe Storms And Flooding |
| 2013 | Flood | Severe Storms, Straight-Line Winds, And Flooding |
| 2011 | Snowstorm | Severe Winter Storm And Snowstorm |
| 2008 | Severe Storm | Severe Storms And Flooding |
| 2005 | Hurricane | Hurricane Katrina Evacuation |
| 2001 | Flood | Flooding |
| 1999 | Snowstorm | Il-Winter Storm 1/1/99 |
| 1993 | Flood | Severe Storms & Flooding |
Showing the 10 most recent of 15 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 | Very Low | 1.1 | 0 | 0 | — |
| Inland Flooding | Very Low | 9.2 | 20 | 0 | $200K |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Very Low | 24.7 | — | — | — |
| Heat Wave | Relatively Low | 48.5 | 0 | 0 | — |
| Tornado | Very Low | 22.5 | 11 | 0 | $25K |
| Hurricane | Very Low | 11.3 | 0 | 0 | — |
| Hail | Very Low | 29.5 | 21 | 0 | — |
| Strong Wind | Relatively Moderate | 61.6 | 0 | 0 | — |
| Winter Weather | Relatively Low | 26.9 | 0 | 0 | — |
| Ice Storm | Relatively Moderate | 66.3 | — | — | — |
| Cold Wave | Relatively Low | 33.4 | — | — | — |
| Lightning | Relatively Moderate | 58.1 | 0 | 0 | — |
| Drought | Relatively Moderate | 71.5 | 0 | 0 | — |
| Landslide | Relatively Low | 68.1 | 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
Mercer County ranks in the 6th percentile (Very 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 | 6th | Very low |
| Socioeconomic status | 14th | Very low |
| Household characteristics | 28th | Low |
| Racial & ethnic minority status | 9th | Very low |
| Housing type & transportation | 5th | Very low |
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 | 19th | Very Low |
| Risk to homes | 19th | Very Low |
| Buildings in direct exposure zone | 33.0% | — |
NOAA tracked 51 weather events in this county over 2016–2025: 25 in 2016–20 vs 26 in 2021–25 (+4% — relatively stable).
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 Mercer County?
According to the FEMA National Risk Index, the highest-risk hazards in Mercer County, Illinois are drought, landslide, and ice storm. The county's overall natural hazard risk is rated Very Low — among the lowest-risk counties in the country.
Has Mercer County received federal disaster declarations?
Yes. Mercer County has received 15 federal disaster declarations since 1965, including declarations in 2020. The most common disaster type on record is flood (7 declarations).
Has Mercer County had any FEMA disaster declarations in 2024, 2025, or 2026?
No federal disaster declarations have been recorded for Mercer County since the start of 2024. Its most recent declaration on record is Covid-19 in 2020.
How does Mercer County's natural hazard risk compare to nearby counties?
Among neighboring counties, Rock Island County, IL has the highest overall natural hazard risk (Relatively Moderate) and Warren County, IL has the lowest (Very Low). Mercer County is rated Very Low overall.
How is Mercer County's composite disaster risk index calculated?
Mercer 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. Mercer County's composite score of 9 means its overall natural hazard risk is higher than 9% of US counties.