U.S. Frost Dates by Weather Station

NOAA station USC00248569 · Montana

Frost Dates for Vida, MT

NOAA weather station Vida 6 NE (USC00248569), Montana · elevation 2284 ft (696 m) · hardiness zone 4a*

  • Lower-risk planting dateafter May 31only 1 spring in 10 still has a frost later
  • Typical last frostMay 1650% chance of a frost after it
  • Typical first fall frostSeptember 2250% chance of a frost before it
  • Frost-free season129 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Vida, MTSpring: a frost after May 2 in 9 years out of 10, after May 16 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 22 in half of the years, before October 4 in 9 years out of 10. Typical frost-free season: 129 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 16First frost ~Sep 22Frost season at Vida, MTSpring: a frost after May 2 in 9 years out of 10, after May 16 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 22 in half of the years, before October 4 in 9 years out of 10. Typical frost-free season: 129 days.JFMAMJJASONDLast frost ~May 16First frost ~Sep 22
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)May 31September 10
50% (typical)May 16September 22
90% (likely)May 2October 4
Frost-free season (32°F, 50% chance)
129 days
Hard frost (28°F), last in spring, 50% chance after
May 4
Hard frost (28°F), first in fall, 50% chance before
October 1

The last 15 years (2006–2020 normals)

Typical last frost May 15 (1 day earlier than the 30-year normal), typical first fall frost September 25 (3 days later). Frost-free season 133 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 Vida: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 31, 20% May 25, 30% May 21, 40% May 18, 50% May 16, 60% May 13, 70% May 10, 80% May 7, 90% May 2.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 31May 16May 2Fall at Vida: chance of a frost before this dateFall, chance of a frost before the date: 10% September 10, 20% September 15, 30% September 18, 40% September 21, 50% September 22, 60% September 25, 70% September 27, 80% September 30, 90% October 4. Observed first fall frost in recent years: 2021 October 10.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 10Sep 22Oct 42021: October 10
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
2021incomplete recordOctober 10
2022incomplete recordno data
2023no datano data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

May 31 is the cautious spring date for tender crops, giving a gardener only a 10% chance that a light frost will occur later in the season, so planting can begin with minimal risk.

The 50% light-frost date in spring is May 16, representing an even chance of frost. The cautious fall date for tender crops is September 10, when there is only a 10% chance that a light frost has already arrived, allowing harvest to continue safely. The 50% light-frost date in fall is September 22, also representing an even chance of frost. The median hard-frost dates are May 4 in spring and October 1 in fall; hard frosts are measured at 28°F.

A hard frost at 28°F matters more than a light frost at 32°F because the lower temperature can freeze plant tissues that survive a light frost.

How to read the probabilities

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

  • Spring: "10% after May 31" 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 September 10" 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 Vida, MTNumbered nearest stations: 1 — Circle, MT — 34 mi; 2 — Culbertson, MT — 44 mi; 3 — Bredette, MT — 44 mi; 4 — Brockway, MT — 46 mi; 5 — Fort Peck Power Plant, MT — 49 mi.MTND25 mi · 40 km1. Circle, MT — 34 mi12. Culbertson, MT — 44 mi23. Bredette, MT — 44 mi34. Brockway, MT — 46 mi45. Fort Peck Power Plant, MT — 49 mi5
  1. Circle, MT 34 mi (55 km)
  2. Culbertson, MT 44 mi (71 km)
  3. Bredette, MT 44 mi (71 km)
  4. Brockway, MT 46 mi (74 km)
  5. Fort Peck Power Plant, MT 49 mi (79 km)

Sources

* Hardiness zone 4a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 47.88, -105.3686.