St. Mary's County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within St. Mary's County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every storm within 100 miles

1. Tropical storms and hurricanes (34 kt or more, still tropical) at closest approach. Post-tropical remnants with gale-force winds are listed but not counted. Direct: track within 50 miles; near: within 100 miles. Distance is measured to the county boundary for counties and to the city centre for cities, using positions interpolated hourly between HURDAT2 fixes.

National Hurricane Center HURDAT2, 1851 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

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).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

More event types since 1996

Costliest events since 1996

1. Sep 18, 2003Tropical Storm, St. Mary'S$86.2 million
   National Weather Service narrative

   On September 18, 2003, Hurricane Isabel made landfall on the North Carolina Coast. Its huge wind field was already piling water up into the southern Chesapeake Bay. By the time Isabel moved into central Virginia, it had weakened and was downgraded to a tropical storm. Isabel's eye tracked well west of the bay, but the storm's 40 to 50 mph sustained winds pushed a bulge of water northward up the bay and its tributaries producing a record storm surge. The Maryland western shore counties of the Chesapeake Bay and along the tidal tributaries of the Potomac, Patuxent, Patapsco and other smaller rivers experience a storm surge reached 5 to 9 feet above normal tides. In many locations,…

2. Jul 29, 2023Thunderstorm Wind$5.0 million
   National Weather Service narrative

   Hundreds of trees blew down around Charlotte Hall, Golden Beach, and Mechanicsville. Many trees blew down onto houses and cars. Numerous trees blew down along Golden Beach Road and on northbound MD-5 Leonardtown Road near Charlotte Hall and Golden Beach. Numerous trees blew down on MD-6 New Market Turner Road between Four Seasons Court and Flora Corner Road. Large trees blew down near the intersection of MD-6 New Market Turner Road and Lockes Hill Road. Dozens of trees blew down around Mechanicsville, with one trapping a sherriff.

3. Aug 27, 2011Tropical Storm, St. Mary'S$3.8 million
   National Weather Service narrative

   Hundreds of trees and power lines were down across the county. Numerous Roads were closed due to downed trees. An unknown number of trees fell onto homes and cars.

4. Sep 1, 2006High Wind, St. Mary'S$3.3 million
   National Weather Service narrative

   Catastrophic damages were sustained in extreme Lower Southern Maryland from the remnants of Tropical Storm Ernesto. Most of the damages were caused by the high winds, although damages were also sustained due to extensive storm surge flooding of coastal areas. High winds persisted for much of the day and evening in Lower Southern Maryland due to the remnants of Tropical Storm Ernesto moving through the Mid Atlantic. Wind gusts as high as 60 mph were reported in St. Mary's County. Wind gusts as high as 70 mph were reported from the public, however these winds were not able to be substantiated. These winds, coupled with heavy rains, caused extensive tree and powerline damage around…

5. Oct 29, 2012High Wind, St. Mary'S$1.4 million
   National Weather Service narrative

   Wind gusts of 58-64 mph were measured at Patuxent Naval Base and Webster Naval Field. There were less than a dozen trees down county wide with minor property damage and one trailer destroyed by a falling tree.

6. Jun 27, 2006Tornado$1.0 million
   National Weather Service narrative

   A waterspout came onshore from the Chesapeake Bay near Chaptico as a tornado, and caused structural damage to several properties in addition to extensive tree damage. The storm destroyed six barns and a carport at two farms along Hurry Road, and also destroyed a barn off Beavan Lane. Several homes and commercial buildings were also damaged. Since an official damage survey was not conducted, the path length, width and F scale rating were estimated based on reports from Emergency Management and newspapers.

7. Aug 4, 2020Tropical Storm, St. Mary'S$750,000
   National Weather Service narrative

   Tropical Storm Force winds observed at Patuxent River Naval Air Station ASOS (KNHK) with sustained winds of 40 mph at 8:04 AM EST, and a peak wind gust of 58 mph at 9:12 AM EST. Also observed at St. Indigoes MD ASOS (KNUI) with sustained winds of 30 mph at 7:53 AM EST, and a peak wind gust of 52 mph at 8:35 AM EST. Dozens of reports of trees down in a few areas as a result of these winds, one of which fell onto a vehicle in motion, killing the motorist. There was also an EF-0 tornado near Scotland, MD and an EF-1 tornado near Piney Point, MD.

8. Sep 16, 1999Flash Flood$500,000
   National Weather Service narrative

   26 people rescued from high water, many streams including St. Mary's River overflowed

9. Jun 30, 2024Thunderstorm Wind$250,000
   National Weather Service narrative

   There were dozens of calls for hundreds of large trees, tree limbs, and wires blown down in the northern end of Saint Mary's County near Charlotte Hall, Mechanicsville, and Golden Beach.

10. Jun 4, 2008Lightning$250,000
    National Weather Service narrative

    A local newspaper reported that a lightning-sparked fire destroyed a home on Brookstone Way in Hermanville.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

104°F3 times, most recently Jun 25, 2025

All-time low

−3°F2 times, most recently Jan 17, 1977

Warmest night

85°FAug 12, 2005

Coldest day

10°FJan 19, 1994

Wettest day

11.76 inSep 30, 2010

Snowiest day

17.6 inJan 7, 1996

Hottest year

2024mean 62.0°F

Coldest year

1988mean 55.2°F

Wettest year

201863.66 in

Driest year

196328.25 in

Station Patuxent River NAS (USW00013721), 39 ft elevation, 8.8 miles from the population centre. Daily records from 1945 to October 26, 2026; 89.4% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

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).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00013721.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.