Sanford, CO 81151 Frost Dates
81151, near Sanford, CO: the frost window
The last spring frost here typically falls around 05/28, about 273 days from today. Fall's first freeze usually shows up around 09/21, roughly 115 days after the last spring frost.
Zone 5a (-20 to -15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Sanford, not a forecast for this year.
Stretching the season past the first frost
Sanford's growing season runs out in roughly 3 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/28 isn't a guarantee
05/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/13 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/11 and only about 1 year in 10 sees frost after that.
Sanford against the rest of the dataset
Sanford's growing season runs about 115 days, ranking 39,323 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 481 of 624.
Learn more
Two guides worth reading on 81151: local microclimates, on what one yard in Sanford can differ from the 81151 normal, and zone vs. frost date, on why Zone 5a and Sanford's frost date answer different questions.