U.S. Frost Dates by Weather Station

NOAA station USC00058793 · Colorado

Frost Dates for Walsh, CO

NOAA weather station Walsh 1 W (USC00058793), Colorado · elevation 3978 ft (1213 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 12only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 1450% chance of a frost before it
  • Frost-free season166 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Walsh, COSpring: a frost after April 17 in 9 years out of 10, after April 30 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 14 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 166 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 14Frost season at Walsh, COSpring: a frost after April 17 in 9 years out of 10, after April 30 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 14 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 166 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 14
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 12October 1
50% (typical)April 30October 14
90% (likely)April 17October 24
Frost-free season (32°F, 50% chance)
166 days
Hard frost (28°F), last in spring, 50% chance after
April 19
Hard frost (28°F), first in fall, 50% chance before
October 22

The last 15 years (2006–2020 normals)

Typical last frost April 30 (same as the 30-year normal), typical first fall frost October 16 (2 days later). Frost-free season 167 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 Walsh: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 12, 20% May 7, 30% May 4, 40% May 2, 50% April 30, 60% April 28, 70% April 24, 80% April 20, 90% April 17. Observed last spring frost in recent years: 2021 April 24, 2022 May 1, 2023 April 22, 2024 April 12, 2025 May 3, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1May 12Apr 30Apr 172021: April 242022: May 12023: April 222024: April 122025: May 32026: May 7Fall at Walsh: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 5, 30% October 8, 40% October 11, 50% October 14, 60% October 16, 70% October 18, 80% October 21, 90% October 24. Observed first fall frost in recent years: 2021 October 15, 2022 October 17, 2023 October 14, 2024 October 16, 2025 October 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 14Oct 242021: October 152022: October 172023: October 142024: October 162025: October 19
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
2021April 24October 15
2022May 1October 17
2023April 22October 14
2024April 12October 16
2025May 3October 19
2026May 7season not over yet

What these dates mean

Setting out tender crops on the early spring date, April 17, carries a 90% chance of a frost later in the season, making it a gamble for Walsh growers. Similarly, counting on tender crops to survive until October 24 involves a 90% chance of an earlier frost, also a gamble.

The 50% dates—April 30 for spring and October 14 for fall—mark the point at which a light frost is equally likely to occur later (spring) or earlier (fall). A cautious plan therefore uses the May 12 light-frost date, which has only a 10% chance of a later frost, for setting out tender crops, and the October 1 date, which has only a 10% chance of an earlier frost, for finishing harvest of tender crops. Hard frosts at 28 °F, recorded median on April 19 and October 22, can damage plants more severely than the 32 °F light frosts because they occur at a lower temperature.

How to read the probabilities

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

  • Spring: "10% after May 12" 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 October 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 Walsh, CONumbered nearest stations: 1 — Lamar, CO — 52 mi; 2 — Hugoton, KS — 55 mi; 3 — Kim 15 NNE, CO — 56 mi; 4 — Ulysses, KS — 57 mi; 5 — Kim 10 SSE, CO — 58 mi.COKS25 mi · 40 km1. Lamar, CO — 52 mi12. Hugoton, KS — 55 mi23. Kim 15 NNE, CO — 56 mi34. Ulysses, KS — 57 mi45. Kim 10 SSE, CO — 58 mi5
  1. Lamar, CO 52 mi (84 km)
  2. Hugoton, KS 55 mi (88 km)
  3. Kim 15 NNE, CO 56 mi (91 km)
  4. Ulysses, KS 57 mi (92 km)
  5. Kim 10 SSE, CO 58 mi (93 km)

Sources

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

Station coordinates: 37.3822, -102.2986.