Billings, MT 59106 Frost Dates
When can you plant in Billings, MT?
Around 05/05 is the usual last spring frost, about 250 days away. The first fall frost typically arrives around 10/03, about 149 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 Billings, not a forecast for this year.
What to do before the first frost
About 5 weeks of growing season left in Billings 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
05/05 is the middle of 30 years of NOAA records, not a promise. Plant by 04/23 and you're betting against frost in roughly 9 years out of 10. 05/21 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Billings compares
Billings's growing season runs about 149 days, ranking 35,472 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 24 of 392.
Learn more
zone vs. frost date covers why Zone 5a and Billings's frost date answer different questions. the frost range covers how to read the range around Billings's dates instead of trusting one.