Mercer County, Missouri: Natural Disaster Risk and History
Mercer County, Missouri has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 12.3 out of 100, higher than about 12% of US counties, with landslides, drought and wildfires scoring highest of its 18 hazards and $4.0 million a year in expected losses.
OpenFEMA lists 18 federal disaster declarations that included Mercer County since 1973, not counting 2 for COVID-19; the latest is DR-4929-MO (Severe Storms, Straight-Line Winds, Tornadoes, and Flooding, declared 3 August 2026). NOAA's Storm Prediction Center recorded 15 tornadoes touching Mercer County from 1950 to 2025.
Live weather alerts for Missouri All official warnings Latest FEMA declarations
Population 3,538 Buildings worth $1.5 billion Area 460 sq mi Risk rank in Missouri 111 of 115 FIPS 29129
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Landslide | Relatively Low | 79.0 | $10,577 | about once every 2.4 years | — |
| Drought | Relatively Moderate | 77.4 | $587,183 | about 12 a year | 322 |
| Wildfire | Very Low | 48.3 | $32,276 | about once every 855 years | — |
| Heat wave | Relatively Low | 46.3 | $229,996 | about 8.5 a year | 111 |
| Tornado | Relatively Low | 44.0 | $754,659 | about once every 4.1 years | 12 |
| Hail | Relatively Low | 42.5 | $144,939 | about 4.1 a year | 155 |
| Cold wave | Relatively Low | 34.8 | $388,577 | about 4.7 a year | 89 |
| Strong wind | Relatively Low | 20.5 | $138,103 | about 3.4 a year | 130 |
| Inland flooding | Very Low | 17.9 | $1.6 million | about once every 2.5 years | 11 |
| Earthquake | Very Low | 17.2 | $16,369 | rarer than once in 1,000 years | — |
| Winter weather | Very Low | 17.1 | $10,772 | about 11 a year | 207 |
| Hurricane | Very Low | 11.4 | $1,778 | about once every 117 years | 0 |
| Lightning | Very Low | 9.4 | $23,095 | about 47 a year | 35,617 strikes |
| Ice storm | Very Low | 9.1 | $3,444 | about once every 4.6 years | 15 |
| Avalanche | Not Applicable | — | — | — | — |
| Coastal flooding | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 18
Most common: Severe Storm 11, Severe Ice Storm 3, Flood 2, Hurricane 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 3 | Drought, Flood, Severe Storm |
| 1990s | 2 | Severe Storm, Flood |
| 2000s | 8 | Severe Storm ×4, Severe Ice Storm ×3, Hurricane |
| 2010s | 4 | Severe Storm ×4 |
| 2020s | 1 | Severe Storm |
The last 10
Widest declarations that included Mercer County
- Severe Winter Storm (2011, EM-3317-MO): 115 Missouri counties designated.
- Severe Winter Storm (2009, EM-3303-MO): 115 Missouri counties designated.
- Severe Winter Storms (2007, EM-3281-MO): 115 Missouri counties designated.
Named storms in its declarations: Hurricane Katrina (2005).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Missouri also had 4 statewide declarations with no county list.
Tornado record since 1950 15
| Tornadoes touching the county | 15 |
|---|---|
| Strongest-rated | (E)F4 ×1 |
| Peak month | April (4) |
| Deadliest | 21 Apr 1973, F4, 14.6 mi path, 0 killed, 1 injured |
| Longest path | 16 Apr 1960, F2, 29.6 mi path |
| Most recent | 27 Apr 2024, EF0, 4 mi path |
| Deaths / injuries on those paths | 0 / 1 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 6 | 6 | 2 | 0 | 1 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 5 | 2 | 1 | 0 | 0 | 2 | 4 | 1 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Mercer County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Mercer County (this page) | — | Very Low | 12.3 | Landslide |
| Grundy County | 34 km | Very Low | 27.9 | Drought |
| Harrison County | 37 km | Very Low | 29.3 | Drought |
| Decatur County, IA | 40 km | Very Low | 23.6 | Drought |
| Wayne County, IA | 41 km | Very Low | 22.0 | Drought |
| Sullivan County | 45 km | Very Low | 10.1 | Landslide |
Nearest by distance between county centres. Every county in Missouri, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively High 73.8 |
|---|---|
| Community resilience | Very Low 12.7 |
| Community risk factor | 1.41 |
| Expected annual loss, all hazards | $4.0 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Mercer County's main hazards
- Right now: National Weather Service alerts for Missouri · all official warnings on Global Incident Tracker.
- Landslide: Landslides recorded
- Drought: Drought monitor for Missouri
- Wildfire: US wildfires now · Wildfire smoke: what protects you
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Mercer County
What natural disasters is Mercer County, Missouri most at risk from?
Mercer County, Missouri has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 12.3 out of 100, higher than about 12% of US counties, with landslides, drought and wildfires scoring highest of its 18 hazards and $4.0 million a year in expected losses.
How many federal disaster declarations has Mercer County had?
OpenFEMA lists 18 federal disaster declarations that included Mercer County since 1973, not counting 2 for COVID-19; the latest is DR-4929-MO (Severe Storms, Straight-Line Winds, Tornadoes, and Flooding, declared 3 August 2026). Another 4 Missouri declarations were made statewide without a county list.
How many tornadoes have hit Mercer County?
NOAA's Storm Prediction Center recorded 15 tornadoes touching Mercer County from 1950 to 2025. The deadliest: 21 Apr 1973, F4, 14.6 mi path, 0 killed, 1 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.