St. Mary's County Climate
St. Mary's County, Maryland
Avg Annual Temp
57.3°F
Annual Precip
46.6"
Annual Snowfall
13.8"
Extreme Heat Days
23.733333333333334
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About St. Mary's County Weather
Warm and Subtropical Environment
A 57.3°F average annual temperature puts St. Mary's County far above the national median. It receives 46.6 inches of precipitation annually, typical of the East Coast.
A Leader in Maryland Warmth
The county is significantly warmer than the Maryland state average of 55.9°F. Its southern coastal location provides one of the mildest winters in the state.
Milder Extremes than Prince George's
St. Mary's is warmer overall than Prince George's County but has 11 fewer extreme heat days. This coastal influence keeps the climate more tempered and stable.
Mild Winters and Warm Summers
Winters are gentle with only 13.8 inches of snow and a 36.6°F January average. July is warm at 78.0°F, though the county only hits 90°F about 24 times a year.
Light Winter Gear Required
With only 13.8 inches of annual snow, heavy winter equipment is rarely needed. Focus on maintaining property against humidity and moderate summer heatwaves.
Frequently Asked Questions
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Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020.
Climate normals are 30-year averages of weather variables computed from 1991 to 2020. Station data is aggregated to county level using spatial averaging. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.