Denton, MT 59430 Frost Dates
Frost dates for Denton, MT, ZIP 59430
The last spring frost here typically falls around 06/01, about 277 days from today. The first fall frost typically arrives around 09/11, about 101 frost-free days later.
Zone 4b (-25 to -20°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 Denton, not a forecast for this year.
What to do before the first frost
Zone 4b around Denton has about 2 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.
How much risk comes with planting early here
06/01 is the middle of 30 years of NOAA records, not a promise. Plant by 05/15 and you're betting against frost in roughly 9 years out of 10. 06/26 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Denton compares
About 101 days separate Denton's last and first frost, putting it 39,691 of 40,283 ZIP codes nationally. Within MT, it ranks 299 of 392.
Learn more
local microclimates explains what one yard in Denton can differ from the 59430 normal, and zone vs. frost date explains why Zone 4b and Denton's frost date answer different questions.