Jamestown, CO 80502 Frost Dates
Jamestown, CO: when does the frost end?
Typically, the last spring freeze lands around 05/06, roughly 251 days out. Fall's first freeze usually shows up around 10/05, roughly 151 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Jamestown in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 5 weeks until Jamestown's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/24 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/18 and only about 1 year in 10 sees frost after that.
Jamestown against the rest of the dataset
At roughly 151 frost-free days, Jamestown places 35,173 of 40,283 ZIP codes in this dataset. Within CO, it ranks 320 of 624.
Learn more
Before leaning on 80502's figures: local microclimates explains what one yard in Jamestown can differ from the 80502 normal, while zone vs. frost date explains why Zone 5b and Jamestown's frost date answer different questions.