Dillon, MT 59732 Frost Dates
Dillon, MT: when does the frost end?
Typically, the last spring freeze lands around 06/05, roughly 281 days out. Fall's first freeze usually shows up around 09/13, roughly 98 days after the last spring frost.
Dillon sits in USDA Zone 4b (-25 to -20°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 2 weeks until Dillon's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
06/05 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/23 and only about 1 year in 10 sees frost after that.
Dillon against the rest of the dataset
About 98 days separate Dillon's last and first frost, putting it 39,757 of 40,283 ZIP codes nationally. Within MT, it ranks 321 of 392.
Learn more
Before leaning on 59732's figures: local microclimates explains what one yard in Dillon can differ from the 59732 normal, while zone vs. frost date explains why Zone 4b and Dillon's frost date answer different questions.