Jefferson County Climate
Jefferson County, New York
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
45.8°F
Annual Precip
40.7"
Annual Snowfall
116.4"
Extreme Heat Days
3
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5a
Minimum winter temperature range for plant survival
2,377
Favors cool-season crops
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 45.8°F annually, moderately wet with 40.7 inches of annual precipitation, rare extreme heat with only 2.95 days above 90°F annually, heavy winter snowfall averaging 116.4 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 19.9°F. summers are pleasantly cool with July averaging 70.0°F. Residents experience a substantial 50°F difference between winter and summer.
Outdoor & Gardening Guidance
Winter sports enthusiasts benefit from reliable snow cover for 3-4 months annually.
Regional Context
Jefferson County closely matches the New York statewide average temperature of 47.5°F, it is somewhat drier than average for New York.
Climate Profile
About Jefferson County Weather
Lake Ontario's Heavy Influence
Jefferson's 45.8°F average temperature is slightly below the national median, but its 116.4 inches of snow is exceptional. This lake-effect climate creates dramatic winter weather shifts.
Cooler and Much Snowier
The county is slightly cooler than the New York average of 47.4°F but is among the state leaders for snowfall. Its 116.4 inches of annual snow is nearly triple the state's typical accumulation.
Warmer than the Adirondacks
Jefferson is warmer than neighboring Franklin (41.3°F) and Hamilton (41.0°F) due to lake moderation. However, it faces more snow than Franklin, though less than the extreme totals in Herkimer.
A Classic Lake-Effect Cycle
July is warm at 70.0°F with only 3 days of extreme heat. January dips to 19.9°F, bringing the bulk of the county's 116.4 inches of annual snowfall.
Winterize Against the Wind
Focus on high-quality weatherstripping and insulation to combat the lake-effect winds. Maintain reliable snow removal services to manage the frequent and heavy 116-inch annual snowfall.
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.