Ambrose, ND 58833 Frost Dates
Frost dates for Ambrose, ND, ZIP 58833
The last spring frost here typically falls around 05/17, about 262 days from today. The first fall frost typically arrives around 09/23, about 128 frost-free days later.
Zone 4a (-30 to -25°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 Ambrose, not a forecast for this year.
What to do before the first frost
Zone 4a around Ambrose has about 4 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.
Why 05/17 isn't a guarantee
05/17 is the middle of 30 years of NOAA records, not a promise. Plant by 05/06 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 Ambrose compares
Ambrose's growing season runs about 128 days, ranking 38,599 of 40,283 US ZIP codes measured here, longest to shortest. Within ND, it ranks 333 of 405.
Learn more
local microclimates explains what one yard in Ambrose can differ from the 58833 normal, and zone vs. frost date explains why Zone 4a and Ambrose's frost date answer different questions.