St. Mary's County, Maryland: Natural Disaster Risk and History
St. Mary's County, Maryland has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 42.6 out of 100, higher than about 42% of US counties, with hurricanes, drought and heat waves scoring highest of its 18 hazards and $22 million a year in expected losses.
OpenFEMA lists 16 federal disaster declarations that included St. Mary's County since 1977, not counting 2 for COVID-19; the latest is EM-3634-MD (Severe Winter Storm, declared 24 January 2026). NOAA's Storm Prediction Center recorded 34 tornadoes touching St. Mary's County from 1950 to 2025.
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Population 113,699 Buildings worth $24 billion Area 772 sq mi Risk rank in Maryland 19 of 24 FIPS 24037
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Hurricane | Relatively Moderate | 85.1 | $6.4 million | about once every 8.3 years | 56 |
| Drought | Relatively Moderate | 72.3 | $1.0 million | about 3.6 a year | 105 |
| Heat wave | Relatively Low | 67.3 | $1.4 million | about 6.3 a year | 105 |
| Strong wind | Relatively Moderate | 65.2 | $1.4 million | about 4.7 a year | 101 |
| Coastal flooding | Relatively Moderate | 63.0 | $1.1 million | about 3.7 a year | — |
| Wildfire | Very Low | 59.0 | $132,193 | rarer than once in 1,000 years | — |
| Winter weather | Relatively Low | 58.1 | $143,227 | about 6.5 a year | 124 |
| Earthquake | Very Low | 57.2 | $669,547 | about once every 746 years | — |
| Lightning | Relatively Low | 56.2 | $489,822 | about 39 a year | 72,588 strikes |
| Ice storm | Relatively Low | 53.8 | $167,054 | about once every 2.0 years | 20 |
| Landslide | Very Low | 51.4 | $2,461 | about once every 11 years | — |
| Tornado | Relatively Low | 39.4 | $1.4 million | about once every 2.2 years | 34 |
| Inland flooding | Relatively Low | 36.8 | $7.2 million | about 2.6 a year | 72 |
| Hail | Relatively Low | 34.3 | $237,259 | about 2.6 a year | 119 |
| Cold wave | Relatively Low | 28.8 | $654,437 | about 1.1 a year | 20 |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Insufficient Data | — | — | — | — |
| 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 16
Most common: Hurricane 8, Snowstorm 5, Severe Storm 2, Winter Storm 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 1 | Snowstorm |
| 1990s | 4 | Snowstorm ×3, Hurricane |
| 2000s | 3 | Hurricane ×2, Severe Storm |
| 2010s | 6 | Hurricane ×4, Severe Storm, Snowstorm |
| 2020s | 2 | Winter Storm, Hurricane |
The last 10
Widest declarations that included St. Mary's County
- Severe Winter Storm (2026, EM-3634-MD): 24 Maryland counties designated.
- Hurricane Sandy (2012, DR-4091-MD): 24 Maryland counties designated.
- Hurricane Sandy (2012, EM-3349-MD): 24 Maryland counties designated.
Named storms in its declarations: Tropical Storm Isaias (2021), Hurricane Sandy (2012), Hurricane Irene (2011), Hurricane Katrina (2005), Hurricane Isabel (2003), Hurricane Floyd (1999).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Maryland also had 1 statewide declaration with no county list.
Tornado record since 1950 34
| Tornadoes touching the county | 34 |
|---|---|
| Strongest-rated | (E)F2 ×1 |
| Peak month | May (6) |
| Deadliest | 8 May 1984, F1, 3 mi path, 0 killed, 3 injured |
| Longest path | 21 Feb 2014, EF0, 23.6 mi path |
| Most recent | 1 Jul 2025, EF1, 1 mi path |
| Deaths / injuries on those paths | 0 / 4 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 22 | 11 | 1 | 0 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 0 | 1 | 1 | 3 | 7 | 6 | 11 | 5 |
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 St. Mary's County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| St. Mary's County (this page) | — | Very Low | 42.6 | Hurricane |
| Westmoreland County, VA | 27 km | Very Low | 37.4 | Hurricane |
| Calvert County | 28 km | Very Low | 28.9 | Hurricane |
| Charles County | 40 km | Relatively Low | 44.1 | Heat wave |
| Richmond County, VA | 41 km | Very Low | 10.4 | Drought |
| King George County, VA | 48 km | Very Low | 12.8 | Hurricane |
Nearest by distance between county centres. Every county in Maryland, ranked.
Vulnerability and resilience
| Social vulnerability | Very Low 10.6 |
|---|---|
| Community resilience | Very High 93.1 |
| Community risk factor | 0.62 |
| Expected annual loss, all hazards | $22 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 St. Mary's County's main hazards
- Right now: National Weather Service alerts for Maryland · all official warnings on Global Incident Tracker.
- Hurricane: Is there a hurricane now? · Cyclone preparation
- Drought: Drought monitor for Maryland
- Heat wave: Heatstroke warning signs
- 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 St. Mary's County
What natural disasters is St. Mary's County, Maryland most at risk from?
St. Mary's County, Maryland has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 42.6 out of 100, higher than about 42% of US counties, with hurricanes, drought and heat waves scoring highest of its 18 hazards and $22 million a year in expected losses.
How many federal disaster declarations has St. Mary's County had?
OpenFEMA lists 16 federal disaster declarations that included St. Mary's County since 1977, not counting 2 for COVID-19; the latest is EM-3634-MD (Severe Winter Storm, declared 24 January 2026). Another 1 Maryland declarations were made statewide without a county list.
How many tornadoes have hit St. Mary's County?
NOAA's Storm Prediction Center recorded 34 tornadoes touching St. Mary's County from 1950 to 2025. The deadliest: 8 May 1984, F1, 3 mi path, 0 killed, 3 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.