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Frost dates and growing zones in Colorado

12 town pages so far. Zones from the 2023 USDA Plant Hardiness Zone Map, frost dates from NOAA 1991-2020 normals at the nearest weather station.

Towns covered so far in Colorado fall in USDA zones 5b, 6a, 7a. Median dates mean frost comes later (spring) or earlier (fall) in half of years.

Towns

TownZoneMedian last frostMedian first frost
Denver6aMay 4Oct 8
Colorado Springs6aMay 3Oct 8
Aurora6aMay 4Oct 8
Fort Collins5bMay 2Oct 7
Arvada6aMay 5Oct 5
Boulder6aMay 6Oct 5
Castle Rock5bMay 9Oct 2
Broomfield6aMay 2Oct 11
Grand Junction7aApr 28Oct 16
Parker5bMay 9Oct 3
Golden6aMay 5Oct 5
Durango6aMay 21Oct 2

Zones in Colorado