St. Mary's County, Maryland Natural Disaster Risk
FEMA National Risk Index assessment · MD
Very LowComposite Risk Score
National percentile: 43th
St. Mary's County faces very low composite natural disaster risk (NRI Risk Index score 42.6, 43th national percentile), driven primarily by hurricane and drought exposure. Expected annual loss across all 18 hazard types is $22M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates St. Mary's County at very low composite risk, with a National Risk Index score of 42.6 out of 100 — placing it in the 43rd national percentile and among the lowest-risk counties in the country. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in hurricane (tropical cyclones bringing extreme wind, rain, and storm surge) at Medium risk — $6M in expected annual loss and about 0.12 events per year; drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $1M in expected annual loss and about 3.60 events per year; and heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Low risk — $1M in expected annual loss and about 6.26 events per year. Across all hazards, FEMA estimates $22M in expected annual loss for a population of 114K.
Beyond physical exposure, St. Mary's County has a very low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
History supports the rating: St. Mary's County has received 18 federal disaster declarations since 1977, including 8 for hurricane events and 5 for snowstorm events. The most recent was Severe Winter Storm (winter storm), declared in January 2026.
Among 24 Maryland counties, St. Mary's County ranks #19 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hurricane | Medium | 0.12 / yr | $6M |
| Drought | Medium | 3.60 / yr | $1M |
| Heat Wave | Low | 6.26 / yr | $1M |
| Strong Wind | Medium | 4.69 / yr | $1M |
| Coastal Flood | Medium | 3.65 / yr | $1M |
| Wildfire | Very Low | 0.00 / yr | $132K |
| Winter Weather | Low | 6.53 / yr | $143K |
| Earthquake | Very Low | 0.00 / yr | $670K |
| Lightning | Low | 38.47 / yr | $490K |
| Ice Storm | Low | 0.49 / yr | $167K |
| Landslide | Very Low | 0.09 / yr | $2K |
| Tornado | Low | 0.45 / yr | $1M |
| Riverine Flood | Low | 2.57 / yr | $7M |
| Hail | Low | 2.64 / yr | $237K |
| Cold Wave | Low | 1.05 / yr | $654K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
St. Mary's County has received 18 federal disaster declarations since 1977, most recently Severe Winter Storm in January 2026. Most frequent causes: Hurricane (8), Snowstorm (5), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| January 2026 | Winter Storm | Severe Winter Storm |
| February 2021 | Hurricane | Tropical Storm Isaias |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| November 2012 | Hurricane | Hurricane Sandy |
| October 2012 | Hurricane | Hurricane Sandy |
| August 2012 | Severe Storm | Severe Storms and Straight-Line Winds |
| September 2011 | Hurricane | Hurricane Irene |
| August 2011 | Hurricane | Hurricane Irene |
| May 2010 | Snowstorm | Severe Winter Storms and Snowstorms |
Showing the 10 most recent of 18 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for St. Mary's County?
St. Mary's County has a composite FEMA National Risk Index score of 42.6 out of 100, placing it in the Very Low category and the 43th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in St. Mary's County?
The three highest-rated hazards are Hurricane (Medium, $6M EAL), Drought (Medium, $1M EAL), Heat Wave (Low, $1M EAL). These account for most of the county's expected annual losses.
How does St. Mary's County compare to other Maryland counties?
St. Mary's County ranks #19 of 24 Maryland counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has St. Mary's County had?
FEMA records 18 federal disaster declarations for St. Mary's County since 1977, most often 8 for hurricane events and 5 for snowstorm events. The most recent was Severe Winter Storm, declared in January 2026.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. St. Mary's County's $22M EAL is a statistical average, not a guarantee for any specific year or address.