Glen Ullin, ND 58631 Frost Dates
Frost dates for Glen Ullin, ND, ZIP 58631
The last spring frost here typically falls around 05/14, about 259 days from today. The first fall frost typically arrives around 09/29, about 136 frost-free days later.
Glen Ullin sits in USDA Zone 4a (-30 to -25°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 4a around Glen Ullin 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
05/14 is the middle of 30 years of NOAA records, not a promise. Plant by 05/03 and you're betting against frost in roughly 9 years out of 10. 05/28 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Glen Ullin compares
About 136 days separate Glen Ullin's last and first frost, putting it 37,743 of 40,283 ZIP codes nationally. Within ND, it ranks 232 of 405.
Learn more
the frost range explains how to read the range around Glen Ullin's dates instead of trusting one, and local microclimates explains what one yard in Glen Ullin can differ from the 58631 normal.