Sidney, MT 59262 Frost Dates
Sidney, MT: when does the frost end?
The last spring frost here typically falls around 05/12, about 257 days from today. Fall's first freeze usually shows up around 09/25, roughly 135 days after the last spring frost.
Sidney 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.
Stretching the season past the first frost
With roughly 4 weeks until Sidney's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/12 isn't a guarantee
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Sidney against the rest of the dataset
Sidney's growing season runs about 135 days, ranking 37,847 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 97 of 392.
Learn more
Before leaning on 59262's figures: local microclimates explains what one yard in Sidney can differ from the 59262 normal, while zone vs. frost date explains why Zone 4a and Sidney's frost date answer different questions.