U.S. Frost Dates by Weather Station

NOAA station USC00247425 · Montana

Frost Dates for Scobey, MT

NOAA weather station Scobey 4 NW (USC00247425), Montana · elevation 2390 ft (729 m) · hardiness zone 3b*

  • Lower-risk planting dateafter June 13only 1 spring in 10 still has a frost later
  • Typical last frostMay 2850% chance of a frost after it
  • Typical first fall frostSeptember 650% chance of a frost before it
  • Frost-free season99 daystypical year, 32°F
  • Hardiness zone3bcalculated*

The year at a glance

Frost season at Scobey, MTSpring: a frost after May 16 in 9 years out of 10, after May 28 in half of the years, after June 13 in 1 year out of 10. Fall: the first frost comes before August 24 in 1 year out of 10, before September 6 in half of the years, before September 19 in 9 years out of 10. Typical frost-free season: 99 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 28First frost ~Sep 6Frost season at Scobey, MTSpring: a frost after May 16 in 9 years out of 10, after May 28 in half of the years, after June 13 in 1 year out of 10. Fall: the first frost comes before August 24 in 1 year out of 10, before September 6 in half of the years, before September 19 in 9 years out of 10. Typical frost-free season: 99 days.JFMAMJJASONDLast frost ~May 28First frost ~Sep 6
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.

Frost dates (32°F)

Probability of frost, based on 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 13August 24
50% (typical)May 28September 6
90% (likely)May 16September 19
Frost-free season (32°F, 50% chance)
99 days
Hard frost (28°F), last in spring, 50% chance after
May 19
Hard frost (28°F), first in fall, 50% chance before
September 16

The last 15 years (2006–2020 normals)

Typical last frost May 29 (1 day later than the 30-year normal), typical first fall frost September 6. Frost-free season 101 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring at Scobey: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 13, 20% June 5, 30% June 2, 40% May 31, 50% May 28, 60% May 26, 70% May 24, 80% May 20, 90% May 16. Observed last spring frost in recent years: 2021 May 21, 2022 June 3, 2023 May 19, 2024 June 8, 2025 June 9, 2026 May 23.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jun 13May 28May 162021: May 212022: June 32023: May 192024: June 82025: June 92026: May 23Fall at Scobey: chance of a frost before this dateFall, chance of a frost before the date: 10% August 24, 20% August 30, 30% September 1, 40% September 4, 50% September 6, 60% September 9, 70% September 11, 80% September 14, 90% September 19. Observed first fall frost in recent years: 2021 September 17, 2022 September 9, 2023 September 15, 2024 August 8, 2025 September 6.Fall: first frostChance of a frost before this date10%50%90%Aug 1Sep 1Oct 1Aug 24Sep 6Sep 192021: September 172022: September 92023: September 152024: August 82025: September 6
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021May 21September 17
2022June 3September 9
2023May 19September 15
2024June 8August 8
2025June 9September 6
2026May 23season not over yet

What these dates mean

August 24 is the cautious fall date for finishing the harvest of tender crops in Scobey, Montana, because there is only a 10 % chance that a light frost has arrived earlier.

In spring the cautious date for setting out tender crops is June 13, when the probability of a light frost later in the season drops to 10 %; the 50% date is May 28, which marks a 50 % chance of a light frost later than that day. The 50% dates—May 28 for spring and September 6 for fall—indicate the point at which the odds of a light frost are even, helping gardeners gauge risk.

A hard frost at 28 °F is more damaging than a light frost at 32 °F because it can kill plant tissue that survives the milder temperature, and the median hard-frost dates are May 19 and September 16.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after June 13" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before August 24" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near Scobey, MTNumbered nearest stations: 1 — Bredette, MT — 24 mi; 2 — Opheim, MT — 39 mi; 3 — Culbertson, MT — 65 mi; 4 — Westby, MT — 65 mi; 5 — Vida, MT — 66 mi.MTND25 mi · 40 km1. Bredette, MT — 24 mi12. Opheim, MT — 39 mi23. Culbertson, MT — 65 mi34. Westby, MT — 65 mi45. Vida, MT — 66 mi5
  1. Bredette, MT 24 mi (38 km)
  2. Opheim, MT 39 mi (64 km)
  3. Culbertson, MT 65 mi (104 km)
  4. Westby, MT 65 mi (104 km)
  5. Vida, MT 66 mi (107 km)

Sources

* Hardiness zone 3b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 48.8356, -105.4747.