St. Mary's County Climate
St. Mary's County, Maryland
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
57.3°F
Annual Precip
46.6"
Annual Snowfall
13.8"
Extreme Heat Days
24
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
8a
Minimum winter temperature range for plant survival
4,149
Excellent for heat-loving crops
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: St. Mary's County
Climate Verdict
St. Mary's County has a mild, with an average annual temperature of 57.3°F, moderately wet with 46.6 inches of annual precipitation, occasional hot days — 23.733333333333334 per year above 90°F, light snow averaging 13.8 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are cold, with January averaging 36.6°F. summers are warm — July averages 78.0°F. The 41°F seasonal variation provides noticeable but manageable change.
Outdoor & Gardening Guidance
The moderate temperatures support hiking, cycling, and camping comfortably in spring, summer, and fall.
Regional Context
St. Mary's County closely matches the Maryland statewide average temperature of 55.9°F.
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 sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.
Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.