Grand Isle County Climate
Grand Isle County, Vermont
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
46.7°F
Annual Precip
35.0"
Annual Snowfall
50.1"
Extreme Heat Days
6
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5a
Minimum winter temperature range for plant survival
2,576
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Grand Isle County
Climate Verdict
Grand Isle County has a cool, averaging 46.7°F annually, moderate rainfall of 35.0 inches per year, rare extreme heat with only 6.4 days above 90°F annually, moderate snowfall of 50.1 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 19.6°F. summers are warm — July averages 71.7°F. Residents experience a substantial 52°F difference between winter and summer.
Outdoor & Gardening Guidance
Winter sports enthusiasts benefit from reliable snow cover for 3-4 months annually.
Regional Context
Grand Isle County is 3.1°F warmer than the Vermont statewide average of 43.6°F, it is also noticeably drier, receiving 9.2 inches less precipitation than the state average.
Climate Profile
About Grand Isle County Weather
Vermont’s Unique Lake Climate
Grand Isle averages 46.7°F, which is warm for Vermont but still 7 degrees below the national median. Its island geography creates a unique microclimate in Lake Champlain.
Second Warmest in Vermont
The county is 3.1 degrees warmer than the state average, ranking as the second warmest in this data set. The lake water acts as a thermal battery, softening winter's edge.
Drier and Warmer Than Most
Grand Isle's 46.7°F average is much higher than Franklin’s 44.5°F. It is also the driest county in the group, receiving only 35.0 inches of annual precipitation.
Less Snow and Warmer Summers
The county receives only 50.1 inches of snow, the lowest in this group by far. Summers are warm and humid, with July averaging 71.7°F and 6 days of extreme heat.
Focus on Wind and Heat
Lakeside winds can increase the chill, despite the 50-inch snowfall being low for the state. Homeowners should plan for warmer summers compared to the rest of Vermont.
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.