Big Timber, MT 59052 Frost Dates
When can you plant in Big Timber, MT?
Typically, the last spring freeze lands around 06/01, roughly 277 days out. The first fall frost typically arrives around 09/11, about 100 frost-free days later.
Zone 5a (-20 to -15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Big Timber, not a forecast for this year.
What to do before the first frost
About 2 weeks of growing season left in Big Timber before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Big Timber's last frost
06/01 is the middle of 30 years of NOAA records, not a promise. Plant by 05/15 and you're betting against frost in roughly 9 years out of 10. 06/21 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Big Timber compares
About 100 days separate Big Timber's last and first frost, putting it 39,717 of 40,283 ZIP codes nationally. Within MT, it ranks 310 of 392.
Learn more
zone vs. frost date covers why Zone 5a and Big Timber's frost date answer different questions. the frost range covers how to read the range around Big Timber's dates instead of trusting one.