Haswell, CO 81021 Frost Dates
When can you plant in Haswell, CO?
Typically, the last spring freeze lands around 05/03, roughly 248 days out. The first fall frost typically arrives around 10/07, about 155 frost-free days later.
Zone 5b (-15 to -10°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 Haswell, not a forecast for this year.
What to do before the first frost
About 6 weeks of growing season left in Haswell before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Haswell's last frost
05/03 is the middle of 30 years of NOAA records, not a promise. Plant by 04/21 and you're betting against frost in roughly 9 years out of 10. 05/16 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Haswell compares
At roughly 155 frost-free days, Haswell places 34,189 of 40,283 ZIP codes in this dataset. Within CO, it ranks 256 of 624.
Learn more
zone vs. frost date covers why Zone 5b and Haswell's frost date answer different questions. the frost range covers how to read the range around Haswell's dates instead of trusting one.