U.S. Frost Dates by Weather Station

NOAA station USC00058931 · Colorado

Frost Dates for Westcliffe, CO

NOAA weather station Westcliffe (USC00058931), Colorado · elevation 7873 ft (2400 m) · hardiness zone 5a*

  • Lower-risk planting dateafter June 28only 1 spring in 10 still has a frost later
  • Typical last frostJune 1150% chance of a frost after it
  • Typical first fall frostSeptember 950% chance of a frost before it
  • Frost-free season89 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Westcliffe, COSpring: a frost after May 29 in 9 years out of 10, after June 11 in half of the years, after June 28 in 1 year out of 10. Fall: the first frost comes before August 28 in 1 year out of 10, before September 9 in half of the years, before September 23 in 9 years out of 10. Typical frost-free season: 89 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 11First frost ~Sep 9Frost season at Westcliffe, COSpring: a frost after May 29 in 9 years out of 10, after June 11 in half of the years, after June 28 in 1 year out of 10. Fall: the first frost comes before August 28 in 1 year out of 10, before September 9 in half of the years, before September 23 in 9 years out of 10. Typical frost-free season: 89 days.JFMAMJJASONDLast frost ~Jun 11First frost ~Sep 9
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 28August 28
50% (typical)June 11September 9
90% (likely)May 29September 23
Frost-free season (32°F, 50% chance)
89 days
Hard frost (28°F), last in spring, 50% chance after
May 28
Hard frost (28°F), first in fall, 50% chance before
September 20

The last 15 years (2006–2020 normals)

Typical last frost June 9 (2 days earlier than the 30-year normal), typical first fall frost September 12 (3 days later). Frost-free season 95 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 Westcliffe: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 28, 20% June 23, 30% June 18, 40% June 14, 50% June 11, 60% June 7, 70% June 4, 80% June 2, 90% May 29. Observed last spring frost in recent years: 2021 June 12, 2022 June 22, 2023 June 14, 2024 May 31, 2025 May 27, 2026 June 13.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jun 28Jun 11May 292021: June 122022: June 222023: June 142024: May 312025: May 272026: June 13Fall at Westcliffe: chance of a frost before this dateFall, chance of a frost before the date: 10% August 28, 20% September 1, 30% September 4, 40% September 6, 50% September 9, 60% September 11, 70% September 14, 80% September 18, 90% September 23. Observed first fall frost in recent years: 2021 September 18, 2022 September 24, 2023 September 17, 2024 September 23, 2025 September 14.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Aug 28Sep 9Sep 232021: September 182022: September 242023: September 172024: September 232025: 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
2021June 12September 18
2022June 22September 24
2023June 14September 17
2024May 31September 23
2025May 27September 14
2026June 13season not over yet

What these dates mean

June 28 is the cautious spring light-frost date for Westcliffe, with only a 10 % chance of a frost occurring later; a gardener can plan to set out tender crops on or after this day with low risk. The middle of the light-frost window is marked by the 50 % date of June 11, meaning there is an even chance of a frost on either side of that day, while May 29 carries a 90 % chance of a later frost and is a gamble for early planting.

In the fall the cautious light-frost date is August 28, when there is just a 10 % chance that a frost has already arrived, so harvesting tender crops before then is prudent. The 50 % fall date of September 9 splits the risk evenly, and September 23 is a 90 % chance that frost has begun. Hard frost at 28 °F, with median dates of May 28 in spring and September 20 in fall, can damage plants more severely than the milder 32 °F light frost, making those dates crucial for protecting sensitive crops.

How to read the probabilities

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

  • Spring: "10% after June 28" 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 28" 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 Westcliffe, CONumbered nearest stations: 1 — Canon City, CO — 26 mi; 2 — Great Sand Dunes National Park & Preserve, CO — 28 mi; 3 — Sheep Mountain, CO — 31 mi; 4 — Walsenburg, CO — 50 mi; 5 — near Alamosa, CO — 52 mi.CO25 mi · 40 km1. Canon City, CO — 26 mi12. Great Sand Dunes National Park & Preserve, CO — 28 mi23. Sheep Mountain, CO — 31 mi34. Walsenburg, CO — 50 mi45. near Alamosa, CO — 52 mi5
  1. Canon City, CO 26 mi (42 km)
  2. Great Sand Dunes National Park & Preserve, CO 28 mi (44 km)
  3. Sheep Mountain, CO 31 mi (51 km)
  4. Walsenburg, CO 50 mi (81 km)
  5. near Alamosa, CO 52 mi (84 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: 38.1314, -105.4661.