U.S. Frost Dates by Weather Station

NOAA station USC00055706 · Colorado

Frost Dates for Monte Vista, CO

NOAA weather station Monte Vista 2 W (USC00055706), Colorado · elevation 7695 ft (2345 m) · hardiness zone 5a*

  • Lower-risk planting dateafter June 25only 1 spring in 10 still has a frost later
  • Typical last frostJune 1150% chance of a frost after it
  • Typical first fall frostSeptember 1350% chance of a frost before it
  • Frost-free season92 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Monte Vista, COSpring: a frost after June 1 in 9 years out of 10, after June 11 in half of the years, after June 25 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 13 in half of the years, before September 24 in 9 years out of 10. Typical frost-free season: 92 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 11First frost ~Sep 13Frost season at Monte Vista, COSpring: a frost after June 1 in 9 years out of 10, after June 11 in half of the years, after June 25 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 13 in half of the years, before September 24 in 9 years out of 10. Typical frost-free season: 92 days.JFMAMJJASONDLast frost ~Jun 11First frost ~Sep 13
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 25September 1
50% (typical)June 11September 13
90% (likely)June 1September 24
Frost-free season (32°F, 50% chance)
92 days
Hard frost (28°F), last in spring, 50% chance after
May 30
Hard frost (28°F), first in fall, 50% chance before
September 23

The last 15 years (2006–2020 normals)

Typical last frost June 10 (1 day earlier than the 30-year normal), typical first fall frost September 16 (3 days later). Frost-free season 97 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 Monte Vista: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 25, 20% June 20, 30% June 17, 40% June 14, 50% June 11, 60% June 9, 70% June 6, 80% June 4, 90% June 1. Observed last spring frost in recent years: 2021 May 28, 2022 May 31, 2023 June 25, 2025 May 27, 2026 May 31.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jun 25Jun 11Jun 12021: May 282022: May 312023: June 252025: May 272026: May 31Fall at Monte Vista: chance of a frost before this dateFall, chance of a frost before the date: 10% September 1, 20% September 5, 30% September 7, 40% September 11, 50% September 13, 60% September 15, 70% September 17, 80% September 20, 90% September 24. Observed first fall frost in recent years: 2021 September 21, 2022 September 30, 2023 September 20, 2024 September 19, 2025 September 14.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 1Sep 13Sep 242021: September 212022: September 302023: September 202024: September 192025: September 14
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 28September 21
2022May 31September 30
2023June 25September 20
2024incomplete recordSeptember 19
2025May 27September 14
2026May 31season not over yet

What these dates mean

June 25 is the cautious spring date for light frost in Monte Vista; with only a 10% chance that a frost occurs later, it lets a gardener set out tender crops.

The 50% light-frost date in spring is June 11, which means there is a 50% chance of a frost later than this date. In fall the cautious date is September 1, carrying a 10% chance that a frost has arrived earlier, while the 50% fall light-frost date is September 13, indicating a 50% chance of a frost earlier than this date.

Hard-frost dates (28 °F) are May 30 in spring and September 23 in fall; a hard frost is more damaging than a light frost because the lower temperature can injure or kill tender plant tissue.

How to read the probabilities

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

  • Spring: "10% after June 25" 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 1" 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 Monte Vista, CONumbered nearest stations: 1 — near Alamosa, CO — 20 mi; 2 — Great Sand Dunes National Park & Preserve, CO — 38 mi; 3 — Chama, NM — 51 mi; 4 — Sheep Mountain, CO — 53 mi; 5 — Westcliffe, CO — 55 mi.CONM25 mi · 40 km1. near Alamosa, CO — 20 mi12. Great Sand Dunes National Park & Preserve, CO — 38 mi23. Chama, NM — 51 mi34. Sheep Mountain, CO — 53 mi45. Westcliffe, CO — 55 mi5
  1. near Alamosa, CO 20 mi (33 km)
  2. Great Sand Dunes National Park & Preserve, CO 38 mi (62 km)
  3. Chama, NM 51 mi (81 km)
  4. Sheep Mountain, CO 53 mi (85 km)
  5. Westcliffe, CO 55 mi (88 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 37.5811, -106.1867.