Frost dates in Colorado

Across Colorado, the typical last spring frost is around May 9 and the first fall frost around Oct 5. Your own dates depend on where you are in the state; find your county below.

Most of the state's last spring frosts fall between Apr 30 and Jun 12, and its first fall frosts between Sep 11 and Oct 12.

These are the dates with a 50% chance of a 32°F frost on or after (spring) or on or before (fall), so plan tender crops a week or two after the spring date and keep row cover handy. For dates at your exact ZIP code, use the zone and frost date lookup; for what to plant when, see the planting guide by frost date.

Hardiness zones in Colorado: zone 4a, zone 4b, zone 5a, zone 5b, zone 6a, zone 6b, zone 7a

Frost dates by county in Colorado

CountyLast spring frostFirst fall frostGrowing season
AdamsMay 3Oct 9About 159 days
AlamosaMay 21Oct 1About 133 days
ArapahoeMay 5Oct 8About 156 days
ArchuletaJun 9Sep 22About 105 days
BacaApr 30Oct 14About 167 days
BentApr 24Oct 15About 174 days
BoulderMay 7Oct 5About 151 days
BroomfieldMay 2Oct 11About 162 days
ChaffeeMay 29Sep 20About 114 days
CheyenneMay 5Oct 9About 157 days
Clear CreekMay 30Sep 19About 112 days
ConejosMay 28Sep 21About 116 days
CostillaMay 31Sep 23About 115 days
CrowleyMay 3Oct 8About 158 days
CusterJun 11Oct 10About 121 days
DeltaMay 3Oct 9About 159 days
DenverApr 30Oct 12About 165 days
DoloresMay 16Oct 11About 148 days
DouglasMay 9Oct 3About 147 days
EagleJun 21Sep 7About 78 days
El PasoMay 9Oct 6About 150 days
ElbertMay 16Oct 2About 139 days
FremontMay 19Oct 2About 136 days
GarfieldMay 23Oct 3About 133 days
GilpinJun 5Sep 16About 103 days
GrandJun 13Sep 7About 86 days
GunnisonJun 20Sep 8About 80 days
HinsdaleJun 8Sep 17About 101 days
HuerfanoMay 27Oct 4About 130 days
JacksonJun 9Sep 12About 95 days
JeffersonMay 3Oct 7About 157 days
KiowaApr 30Oct 13About 166 days
Kit CarsonMay 6Oct 9About 156 days
La PlataMay 31Sep 27About 119 days
LakeJun 16Sep 10About 86 days
LarimerMay 21Oct 1About 133 days
Las AnimasMay 6Oct 4About 151 days
LincolnMay 9Oct 4About 148 days
LoganMay 4Oct 9About 158 days
MesaApr 26Oct 16About 173 days
MineralJun 15Sep 11About 88 days
MoffatMay 29Sep 20About 114 days
MontezumaMay 17Oct 9About 145 days
MontroseMay 11Oct 8About 150 days
MorganMay 6Oct 6About 153 days
OteroApr 30Oct 10About 163 days
OurayJun 11Oct 1About 112 days
ParkJun 15Sep 9About 86 days
PhillipsMay 11Oct 3About 145 days
PitkinMay 31Sep 23About 115 days
ProwersMay 1Oct 12About 164 days
PuebloApr 30Oct 10About 163 days
Rio BlancoMay 25Sep 25About 123 days
Rio GrandeMay 23Sep 25About 125 days
RouttJun 14Sep 11About 89 days
SaguacheMay 26Sep 26About 123 days
San JuanJun 15Sep 11About 88 days
San MiguelMay 25Oct 1About 129 days
SedgwickMay 6Oct 7About 154 days
SummitJun 21Sep 9About 80 days
TellerMay 26Sep 26About 123 days
WashingtonMay 12Oct 6About 147 days
WeldMay 7Oct 5About 151 days
YumaMay 3Oct 9About 159 days

Source: NOAA NCEI U.S. Climate Normals 1991–2020, 50% probability of 32°F, from the weather station nearest each ZIP code; each county shows the middle value across its ZIP codes. Hills, valleys and cities can run a week or more earlier or later.

Frost dates for other states