Castle Rock, CO 80163 Frost Dates
Frost dates for Castle Rock, CO, ZIP 80163
The last spring frost here typically falls around 05/09, about 254 days from today. The first fall frost typically arrives around 10/02, about 143 frost-free days later.
Castle Rock sits in USDA Zone 6a (-10 to -5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 6a around Castle Rock has about 5 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around Castle Rock's last frost
05/09 is the middle of 30 years of NOAA records, not a promise. Plant by 04/30 and you're betting against frost in roughly 9 years out of 10. 05/24 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Castle Rock compares
About 143 days separate Castle Rock's last and first frost, putting it 36,486 of 40,283 ZIP codes nationally. Within CO, it ranks 380 of 624.
Learn more
zone vs. frost date explains why Zone 6a and Castle Rock's frost date answer different questions, and the frost range explains how to read the range around Castle Rock's dates instead of trusting one.