Melstone, MT 59059 Frost Dates
Frost dates for Melstone, MT, ZIP 59059
Typically, the last spring freeze lands around 05/10, roughly 255 days out. The first fall frost typically arrives around 09/29, about 141 frost-free days later.
The USDA Plant Hardiness Zone Map puts Melstone in Zone 4b (-25 to -20°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 4b around Melstone 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.
How much risk comes with planting early here
05/10 is the middle of 30 years of NOAA records, not a promise. Plant by 04/28 and you're betting against frost in roughly 9 years out of 10. 05/23 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Melstone compares
At roughly 141 frost-free days, Melstone places 37,004 of 40,283 ZIP codes in this dataset. Within MT, it ranks 67 of 392.
Learn more
local microclimates explains what one yard in Melstone can differ from the 59059 normal, and zone vs. frost date explains why Zone 4b and Melstone's frost date answer different questions.