Sullivan County Climate
Sullivan County, New Hampshire
Avg Annual Temp
44.3°F
Annual Precip
42.0"
Annual Snowfall
66.1"
Extreme Heat Days
6.3
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Sullivan County Weather
Sullivan's Cold Northern Reach
Sullivan County maintains a brisk average annual temperature of 44.3°F, placing it nearly 10 degrees below the national median. This region defines the cooler end of the humid continental climate spectrum.
Below the New Hampshire Average
The county sits below the state average annual temperature of 45.4°F and is also slightly drier than most of New Hampshire. It records 42.0 inches of precipitation annually, compared to the 46.4-inch state benchmark.
A More Rugged Interior Climate
Sullivan is much colder and snowier than coastal-adjacent Strafford County, averaging 66.1 inches of snow per year compared to Strafford's 38.9. Its July average of 68.3°F is also two degrees cooler than its eastern neighbors.
Heavy Snow and Brisk Winters
Winter is the dominant season here, with average temperatures of 22.1°F and a January low of 19.2°F. Extreme heat is rare, as the county sees only 6 days a year reaching 90°F or higher.
Gear Up for Serious Snow
With 66.1 inches of annual snowfall, residents require heavy-duty snow removal equipment and dedicated winter tires. Home insulation is a priority given the winter average of 22.1°F, which is lower than many other parts of the state.
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.