Ennis, MT 59740 Frost Dates
Ennis, MT: when does the frost end?
Around 04/30 is the usual last spring frost, about 245 days away. Fall's first freeze usually shows up around 10/10, roughly 162 days after the last spring frost.
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.
Stretching the season past the first frost
With roughly 6 weeks until Ennis's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/30 isn't a guarantee
04/30 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/15 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/14 and only about 1 year in 10 sees frost after that.
Ennis against the rest of the dataset
About 162 days separate Ennis's last and first frost, putting it 31,795 of 40,283 ZIP codes nationally. Within MT, it ranks 8 of 392.
Learn more
Before leaning on 59740's figures: the frost range explains how to read the range around Ennis's dates instead of trusting one, while local microclimates explains what one yard in Ennis can differ from the 59740 normal.