Mercer County, OH
FEMA National Risk Index scores, disaster declarations & hazard data
Mercer County has experienced 14 federally declared disasters since 1965, most recently Tornadoes in 2024. Its overall natural hazard risk is rated Very Low — among the lowest-risk counties in the country.
Mercer County's highest-rated hazards are earthquake, tornado, and hail, with its top risk rated "Relatively Low" by FEMA's National Risk Index. Recorded storm events have decreased 59% over the past five years compared to the prior five-year period. Community vulnerability is relatively low (2nd 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 14 declarations since 1965, covering 6 disaster types including severe storm (6), tornado (3), biological (2).
| Year | Type | Event name |
|---|---|---|
| 2024 | Tornado | Tornadoes |
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2019 | Tornado | Severe Storms, Straight-Line Winds, Tornadoes, Flooding, Landslides, And Mudslide |
| 2012 | Severe Storm | Severe Storms |
| 2005 | Severe Storm | Severe Winter Storms, Flooding, And Mudslides |
| 2005 | Hurricane | Hurricane Katrina Evacuation |
| 2004 | Severe Storm | Severe Storms And Flooding |
| 2003 | Severe Storm | Severe Storms And Flooding |
| 1995 | Severe Storm | Severe Storms And Flooding |
Showing the 10 most recent of 14 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 | 6.5 | 0 | 0 | — |
| Inland Flooding | Relatively Low | 42.1 | 27 | 0 | $585K |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Relatively Low | 73.8 | — | — | — |
| Heat Wave | Very Low | 17.4 | 2 | 0 | — |
| Tornado | Relatively Moderate | 67 | 11 | 1 | $32.9M |
| Hurricane | Very Low | 38.9 | 0 | 0 | — |
| Hail | Relatively Low | 64.1 | 14 | 0 | $1K |
| Strong Wind | Relatively Low | 48.9 | 0 | 0 | — |
| Winter Weather | Relatively Low | 28.3 | 0 | 0 | — |
| Ice Storm | Relatively Low | 45.1 | — | — | — |
| Cold Wave | Relatively Low | 30.4 | — | — | — |
| Lightning | Relatively Low | 25.8 | 0 | 0 | — |
| Drought | No Rating | 0 | 0 | 0 | — |
| Landslide | Very Low | 20.9 | 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 2nd 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 | 2nd | Very low |
| Socioeconomic status | 2nd | Very low |
| Household characteristics | 10th | Very low |
| Racial & ethnic minority status | 6th | Very low |
| Housing type & transportation | 13th | 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 | 1st | Very Low |
| Risk to homes | 1st | Very Low |
| Buildings in direct exposure zone | 21.4% | — |
NOAA tracked 52 weather events in this county over 2016–2025: 37 in 2016–20 vs 15 in 2021–25 (-59% — 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 Mercer County?
According to the FEMA National Risk Index, the highest-risk hazards in Mercer County, Ohio are earthquake, tornado, and hail. 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 14 federal disaster declarations since 1965, including declarations in 2024. The most common disaster type on record is severe storm (6 declarations).
Has Mercer County had any FEMA disaster declarations in 2024, 2025, or 2026?
Yes. Recent federal disaster declarations for Mercer County include Tornadoes (2024). See the declarations table above for the full history since 1965.
How does Mercer County's natural hazard risk compare to nearby counties?
Among neighboring counties, Shelby County, OH has the highest overall natural hazard risk (Relatively Low) and Van Wert County, OH 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 32 means its overall natural hazard risk is higher than 32% of US counties.