Jefferson County Climate
Jefferson County, Idaho
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
44.8°F
Annual Precip
11.2"
Annual Snowfall
20.4"
Extreme Heat Days
22
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5a
Minimum winter temperature range for plant survival
2,054
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 44.8°F annually, arid conditions receiving just 11.2 inches of precipitation annually, occasional hot days — 21.75 per year above 90°F, moderate snowfall of 20.4 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 20.5°F. summers are pleasantly cool with July averaging 69.2°F. The 49°F seasonal variation provides noticeable but manageable change.
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 Idaho statewide average temperature of 46.5°F, it is also noticeably drier, receiving 5.8 inches less precipitation than the state average.
Climate Profile
About Jefferson County Weather
Dry and chilly in the High Desert
Jefferson County maintains a cool annual average of 44.8°F, well below the national median. With only 11.2 inches of annual precipitation, it is significantly drier than the average American county.
Below the Idaho state temperature average
At 44.8°F, the county sits roughly 1.7 degrees cooler than the Idaho statewide average of 46.5°F. Its precipitation level of 11.2 inches is also notably lower than the state's 17-inch average.
Sharing the cold with Idaho County
Jefferson County matches Idaho County's 44.8°F average temperature exactly, despite being on the other side of the state. However, it receives less than half the annual snowfall of its western peer, totaling just 20.4 inches.
Frigid winters and arid summer days
Winter is biting with a January average of 20.5°F, which is much colder than many neighboring regions. July brings relief with a 69.2°F average, though the county still sees 22 days above 90°F.
Winterize for deep freezes
Heating systems must be robust to handle the 20°F January average, and pipes require extra insulation against the dry cold. Summer planning should account for the 22 days of extreme heat despite the generally cool annual average.
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.