Big Timber, MT 59055 Frost Dates
59055, near Big Timber, MT: the frost window
Around 06/09 is the usual last spring frost, about 285 days away. Fall's first freeze usually shows up around 09/07, roughly 88 days after the last spring frost.
Big Timber 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
Big Timber's growing season runs out in roughly 1 week — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
06/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/26 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/27 and only about 1 year in 10 sees frost after that.
Big Timber against the rest of the dataset
At roughly 88 frost-free days, Big Timber places 39,944 of 40,283 ZIP codes in this dataset. Within MT, it ranks 345 of 392.
Learn more
Two guides worth reading on 59055: zone vs. frost date, on why Zone 4b and Big Timber's frost date answer different questions, and the frost range, on how to read the range around Big Timber's dates instead of trusting one.