Custer County Climate
Custer County, Idaho
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
40.8°F
Annual Precip
12.8"
Annual Snowfall
29.5"
Extreme Heat Days
12
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5b
Minimum winter temperature range for plant survival
1,325
Limited to cold-tolerant varieties
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Custer County
Climate Verdict
Custer County has a cool, averaging 40.8°F annually, arid conditions receiving just 12.8 inches of precipitation annually, rare extreme heat with only 11.966666666666669 days above 90°F annually, moderate snowfall of 29.5 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 18.5°F. summers are pleasantly cool with July averaging 64.0°F. The 45°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 Custer County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Custer County is 5.8°F cooler than the Idaho statewide average of 46.5°F, it is somewhat drier than average for Idaho, the county experiences 18.22831751581752 fewer extreme heat days than the state average.
Climate Profile
About Custer County Weather
One of the Nation's Coldest Corridors
Custer County is significantly colder than the national median, posting a chilly annual average of 40.8°F. This mountain climate experiences some of the lowest average temperatures in the lower 48 states.
Well Below the Idaho Temperature Average
Averaging 40.8°F, Custer County is nearly 6 degrees colder than the Idaho state average of 46.5°F. It ranks among the state's coldest regions, characterized by long winters and short growing seasons.
Chillier Than Its Southern Neighbors
Custer County is much colder than nearby Elmore County, which averages 52.6°F. It also receives just 12.8 inches of precipitation, making it as dry as the high deserts to its south.
Frigid Winters and Brief Summer Heat
January temperatures average a freezing 18.5°F, while winter as a whole averages just 20.0°F. Summer provides a quick reprieve with a July average of 64.0°F and only 12 days topping 90°F.
Winterize for Extreme Mountain Cold
Extreme cold dominates the plan here, requiring high-efficiency heating systems and cold-weather survival kits for travel. Despite the cold, the 29.5 inches of snow is manageable compared to the state's wetter northern counties.
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.