Costilla County Climate
Costilla County, Colorado
Avg Annual Temp
43.8°F
Annual Precip
9.4"
Annual Snowfall
—
Extreme Heat Days
3.15
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Costilla County Weather
Costilla: High-Altitude Mountain Valley Climate
At 43.8°F, Costilla County is approximately 5.7 degrees colder than the U.S. median of 49.5°F, placing it solidly in the cold-altitude tier. With 9.4 inches of annual precipitation, Costilla County is significantly drier than the national median of 15.2 inches, though it sits in a rain-shadow valley. This high-elevation, arid mountain climate is characteristic of Colorado's southern uplands.
Costilla: Cold Valley at the State's Edge
Costilla County's 43.8°F average ranks 2.2 degrees below Colorado's state average of 46.0°F, while its 9.4 inches of precipitation fall well short of the state average of 16.0 inches. The county sits in the extreme southern part of Colorado, bordering New Mexico, where elevation and rain-shadow effects combine to create persistent cold and aridity. Its climate is defined by the San Luis Valley's geographic isolation.
Isolated Valley, Similar to Conejos
Costilla County's climate closely mirrors neighboring Conejos County to the west (both at 43.8°F and similarly dry), reflecting their shared San Luis Valley setting. Both counties are noticeably cooler and drier than Huerfano County to the northeast, which benefits from slightly lower elevation and more moisture. Compared to high-plains counties like Las Animas to the east, Costilla is both colder and drier.
Rare Heat, Long Cold, Limited Data
Costilla County experiences just 3 days per year above 90°F, with July temperatures averaging 65.3°F and January dropping to 20.9°F. While annual snowfall data is not available, the county's location and temperature patterns suggest 20–30 inches is typical for the San Luis Valley. The persistent cold and low precipitation create a harsh environment for agriculture and outdoor work.
Plan for Isolation and Extreme Dryness
Residents must account for extreme dryness (9.4 inches annually): invest in long-lasting water systems, drought-resistant landscaping, and indoor humidifiers for winter comfort. The county's remote location and limited precipitation data mean weather forecasting is less precise; stock emergency supplies year-round and maintain vehicles in peak condition for sudden winter weather. Outdoor recreation is best in summer and early fall when temperatures reach 55–65°F; winter drives demand chains and survival kits.
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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.