Glenn County Climate
Glenn County, California
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
62.0°F
Annual Precip
21.5"
Annual Snowfall
0.0"
Extreme Heat Days
95
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
9b
Minimum winter temperature range for plant survival
4,808
Excellent for heat-loving crops
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Glenn County
Climate Verdict
Glenn County has a warm, averaging 62.0°F year-round, semi-arid conditions with only 21.5 inches of annual precipitation, significant summer heat with 95.46666666666665 days annually above 90°F, virtually no measurable snowfall. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are mild, with January temperatures averaging 47.1°F. summers are warm — July averages 78.7°F. The 32°F seasonal variation provides noticeable but manageable change. December is typically the coldest month and July the warmest.
Outdoor & Gardening Guidance
Summer outdoor activities should be planned for early morning or evening to avoid extreme heat.
Regional Context
Glenn County is 3.4°F warmer than the California statewide average of 58.7°F, it is somewhat drier than average for California, the county experiences 36.79574170373278 more extreme heat days than the state average.
Climate Profile
About Glenn County Weather
Warm Interior Mediterranean Climate
Glenn County’s annual average of 62.0°F is significantly higher than the national median temperature. This interior region sees 21.5 inches of rain, placing it in a dry Mediterranean climate zone.
Warmer Than the State Average
Averaging 62.0°F, Glenn is warmer than the California state average of 58.7°F. It sits among the warmer tier of Sacramento Valley counties where heat accumulates away from the coast.
Mirroring the Northern Valley
Its climate closely mirrors neighboring Butte and Colusa counties, which are characterized by hot, dry summers. With 95 extreme heat days, it faces a thermal profile nearly identical to its agricultural neighbors.
Intense Summers and Snowless Winters
Summers are intense with an average of 76.6°F, while winters remain mild at 48.0°F. The county records zero inches of annual snowfall, emphasizing the dominance of the valley's warm air masses.
Manage the High-Heat Days
Homeowners should invest in high-capacity HVAC systems to combat nearly 100 days of temperatures over 90°F. Lightweight summer clothing is essential, while heavy winter gear is rarely necessary given the mild 47.1°F January 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.