Colorado climate almanac
Colorado's climate, read through its 70 NOAA stations, is mainly mild humid continental (northeast, midwest, pacific northwest), then cold continental (upper midwest, rocky mountains), then desert southwest (arizona, nevada, inland california). The mean frost-free season runs from about May 11 to October 3, roughly 134 days.
Stations 70 NOAA 1991-2020 normals
Mean frost-free season 134 days 71 to 173 across the state
Typical frost window May 11 - October 3 Median last and first frost
Main climate types 3 Mild humid continental (Northeast, Midwest, Pacific Northwest) (54); Cold continental (Upper Midwest, Rocky Mountains) (10); Desert Southwest (Arizona, Nevada, inland California) (6)
What this means for your home
In Colorado, the difference between the shortest and longest frost-free pockets is 102 days. That is the difference between a tomato crop that struggles and one that runs into October, between one fertilizer timing and another. Set your place above to tune every date to your nearest station.
Major cities in Colorado
Pick a city to see its frost and planting dates, or set your own place above.