San Juan County Climate
San Juan County, Colorado
Avg Annual Temp
34.7°F
Annual Precip
23.9"
Annual Snowfall
172.6"
Extreme Heat Days
0
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About San Juan County Weather
San Juan: America's coldest county climate zone
San Juan County's 34.7°F annual average is a striking 11.8°F cooler than the national median of 46.5°F, making it one of the coldest climates in the contiguous United States. Its 23.9 inches of annual precipitation and 172.6 inches of snow create an alpine arctic climate found only in Colorado's highest peaks.
Colorado's coldest county by far
San Juan's 34.7°F annual average sits 11.3°F below Colorado's state average of 46.0°F, making it unquestionably the state's coldest county and one of the most extreme climates in the United States. The county's high-elevation San Juan Mountains location creates this unique arctic-alpine environment.
Dramatically colder than all regional peers
San Juan's 34.7°F is 8.8°F colder than Rio Grande County to the east and 8.7°F colder than San Miguel County to the north, making it a climate island among Colorado counties. Its 172.6 inches of snowfall also vastly exceeds regional neighbors, creating a truly unique weather regime.
Zero extreme heat days, perpetual winter threat
San Juan County records zero days per year with temperatures at or above 90°F, while winters plunge to a brutal 15.1°F average with January at 14.3°F and July reaching only 56.5°F. Summer temperatures average just 53.8°F, and the 172.6 inches of annual snowfall—the highest in the dataset—dominate the climate calendar.
Alpine survival mode: extreme cold and snow mandatory
With winter averaging 15°F and 172.6 inches of annual snowfall, residents need industrial-grade heating, advanced insulation, and permanent avalanche/snow management infrastructure. The zero extreme heat days mean air conditioning is completely unnecessary, but year-round winter preparedness, high-altitude vehicle winterization, and emergency supplies are non-negotiable survival priorities.
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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.