Fairfield, MT 59436 Frost Dates
When can you plant in Fairfield, MT?
Around 05/13 is the usual last spring frost, about 258 days away. The first fall frost typically arrives around 09/27, about 135 frost-free days later.
Zone 4b (-25 to -20°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 Fairfield, not a forecast for this year.
What to do before the first frost
About 4 weeks of growing season left in Fairfield before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
05/13 is the middle of 30 years of NOAA records, not a promise. Plant by 04/28 and you're betting against frost in roughly 9 years out of 10. 06/01 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Fairfield compares
Fairfield's growing season runs about 135 days, ranking 37,898 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 100 of 392.
Learn more
the frost range covers how to read the range around Fairfield's dates instead of trusting one. local microclimates covers what one yard in Fairfield can differ from the 59436 normal.