Ennis, MT 59745 Frost Dates
Frost dates for Ennis, MT, ZIP 59745
The last spring frost here typically falls around 04/30, about 245 days from today. The first fall frost typically arrives around 10/10, about 162 frost-free days later.
Ennis sits in USDA Zone 5a (-20 to -15°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 5a around Ennis has about 6 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 04/30 isn't a guarantee
04/30 is the middle of 30 years of NOAA records, not a promise. Plant by 04/15 and you're betting against frost in roughly 9 years out of 10. 05/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Ennis compares
About 162 days separate Ennis's last and first frost, putting it 31,796 of 40,283 ZIP codes nationally. Within MT, it ranks 9 of 392.
Learn more
the frost range explains how to read the range around Ennis's dates instead of trusting one, and local microclimates explains what one yard in Ennis can differ from the 59745 normal.