Chester, MT 59444 Frost Dates
Chester, MT: when does the frost end?
Around 05/23 is the usual last spring frost, about 268 days away. Fall's first freeze usually shows up around 09/14, roughly 112 days after the last spring frost.
Chester 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 2 weeks until Chester's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/23 isn't a guarantee
05/23 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/12 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/08 and only about 1 year in 10 sees frost after that.
Chester against the rest of the dataset
At roughly 112 frost-free days, Chester places 39,429 of 40,283 ZIP codes in this dataset. Within MT, it ranks 263 of 392.
Learn more
Before leaning on 59444's figures: local microclimates explains what one yard in Chester can differ from the 59444 normal, while zone vs. frost date explains why Zone 4a and Chester's frost date answer different questions.