U.S. Frost Dates by Weather Station

NOAA station USC00058781 · Colorado

Frost Dates for Walsenburg, CO

NOAA weather station Walsenburg 1 NW (USC00058781), Colorado · elevation 6292 ft (1918 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 20only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 450% chance of a frost before it
  • Frost-free season149 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Walsenburg, COSpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 4 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 149 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 4Frost season at Walsenburg, COSpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 4 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 149 days.JFMAMJJASONDLast frost ~May 6First frost ~Oct 4
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 20September 23
50% (typical)May 6October 4
90% (likely)April 24October 17
Frost-free season (32°F, 50% chance)
149 days
Hard frost (28°F), last in spring, 50% chance after
April 29
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 9 (3 days later than the 30-year normal), typical first fall frost October 8 (4 days later). Frost-free season 151 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 Walsenburg: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 20, 20% May 15, 30% May 11, 40% May 8, 50% May 6, 60% May 4, 70% May 2, 80% April 29, 90% April 24. Observed last spring frost in recent years: 2021 May 12, 2022 May 22, 2023 April 29, 2024 May 22, 2025 April 29.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 20May 6Apr 242021: May 122022: May 222023: April 292024: May 222025: April 29Fall at Walsenburg: chance of a frost before this dateFall, chance of a frost before the date: 10% September 23, 20% September 27, 30% September 30, 40% October 2, 50% October 4, 60% October 7, 70% October 10, 80% October 14, 90% October 17. Observed first fall frost in recent years: 2021 October 15, 2022 October 13, 2023 October 7, 2024 October 16, 2025 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 23Oct 4Oct 172021: October 152022: October 132023: October 72024: October 162025: October 17
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 12October 15
2022May 22October 13
2023April 29October 7
2024May 22October 16
2025April 29October 17
2026incomplete recordseason not over yet

What these dates mean

The 149 days between the 50% dates of May 6 and October 4 in Walsenburg define the period when most garden work can be scheduled. The May 6 date marks the point at which there is an even chance a light frost (32 °F) will still occur later in spring, while October 4 marks the point at which there is an even chance a light frost will have arrived earlier in fall; neither date is itself a frost date.

The cautious spring date for setting out tender crops is May 20, which carries only a 10 % chance of a frost later, whereas planting on April 24 would involve a 90 % chance and is a gamble. In fall, the cautious date to finish harvesting tender crops is September 23, with only a 10 % chance that a frost has already arrived, while waiting until October 17 would involve a 90 % chance of earlier frost.

Hard frost at 28 °F can damage plants that survive a light frost at 32 °F, so the median hard-frost dates of April 29 and October 15 are especially important.

How to read the probabilities

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

  • Spring: "10% after May 20" 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 23" 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 Walsenburg, CONumbered nearest stations: 1 — Sheep Mountain, CO — 25 mi; 2 — near Trinidad, CO — 36 mi; 3 — Great Sand Dunes National Park & Preserve, CO — 40 mi; 4 — Pueblo, CO — 48 mi; 5 — Westcliffe, CO — 50 mi.CONM25 mi · 40 km1. Sheep Mountain, CO — 25 mi12. near Trinidad, CO — 36 mi23. Great Sand Dunes National Park & Preserve, CO — 40 mi34. Pueblo, CO — 48 mi45. Westcliffe, CO — 50 mi5
  1. Sheep Mountain, CO 25 mi (40 km)
  2. near Trinidad, CO 36 mi (58 km)
  3. Great Sand Dunes National Park & Preserve, CO 40 mi (64 km)
  4. Pueblo, CO 48 mi (78 km)
  5. Westcliffe, CO 50 mi (81 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 37.6303, -104.7956.