Montana Frost Dates
Published: February 1, 2026 · Updated: April 23, 2026
Last Spring Frost
May 7
Zone 4b
First Fall Frost
October 1
Zone 4b
Frost-Free Season
147 days
Early May to Late October
Lawn Care Timing for Montana
Vegetable Garden Timing for Montana
Frost Dates by City in Montana
Frequently Asked Questions
What is the last frost date in Montana?
The average last spring frost in Montana (zone 4b) is May 7. Dates vary by city and elevation. Find your specific city below for exact dates.
When is it safe to plant tomatoes in Montana?
Transplant tomato seedlings outdoors after May 7 — the average last frost date for zone 4b. Start seeds indoors Early March (8 weeks before last frost). Wait 2 weeks after last frost for extra safety.
When should I overseed my lawn in Montana?
The prime overseeding window in Montana is September 1–15. This ensures 6 weeks of warm soil for germination before the first fall frost on October 1.
When should I apply winteriser in Montana?
Apply winteriser fertiliser by Late October. Your first fall frost of October 1 is the hard deadline — apply at least 2–3 weeks before.
What USDA zone is Montana?
Montana contains USDA zones 4b. Each zone has different frost dates and growing seasons. Find your city below for your specific zone.