Jefferson County Climate
Jefferson County, Montana
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
42.6°F
Annual Precip
10.8"
Annual Snowfall
—
Extreme Heat Days
12
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5a
Minimum winter temperature range for plant survival
1,477
Limited to cold-tolerant varieties
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Jefferson County
Climate Verdict
Jefferson County has a cool, averaging 42.6°F annually, arid conditions receiving just 10.8 inches of precipitation annually, rare extreme heat with only 12 days above 90°F annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 23.5°F. summers are pleasantly cool with July averaging 65.4°F. The 42°F seasonal variation provides noticeable but manageable change. December is typically the coldest month and July the warmest.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Jefferson County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Jefferson County closely matches the Montana statewide average temperature of 43.7°F, it is somewhat drier than average for Montana.
Climate Profile
About Jefferson County Weather
A dry climate with cool averages
Jefferson County is notably dry, receiving only 10.8 inches of precipitation per year. Its annual average temperature of 42.6°F is roughly 12 degrees below the national median.
Slightly cooler than the state average
With an average of 42.6°F, Jefferson County is just over a degree cooler than the Montana state average of 43.7°F. It ranks among the more arid counties in the state.
Similar to Granite and Judith Basin
Jefferson County's 42.6°F temperature mirrors Granite County (42.5°F) and is slightly cooler than Judith Basin (43.4°F). It is significantly drier than its neighbor, Glacier County.
Mild summers and low heat risk
Summer heat is moderate here, with only 12 days reaching 90°F and a July average of 65.4°F. While snowfall data is limited, winters stay cold with a January average of 23.5°F.
Focus on moisture and winter heat
With only 10.8 inches of precipitation, water-wise landscaping is essential for residents. Heating remains the primary utility concern, as summer cooling needs are minimal with only 12 extreme heat days.
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.