U.S. Frost Dates by Weather Station

NOAA station USC00054770 · Colorado

Frost Dates for Lamar, CO

NOAA weather station Lamar (USC00054770), Colorado · elevation 3627 ft (1106 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 13only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 1050% chance of a frost before it
  • Frost-free season163 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Lamar, COSpring: a frost after April 17 in 9 years out of 10, after April 30 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 10 in half of the years, before October 21 in 9 years out of 10. Typical frost-free season: 163 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 10Frost season at Lamar, COSpring: a frost after April 17 in 9 years out of 10, after April 30 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 10 in half of the years, before October 21 in 9 years out of 10. Typical frost-free season: 163 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 10
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 13October 1
50% (typical)April 30October 10
90% (likely)April 17October 21
Frost-free season (32°F, 50% chance)
163 days
Hard frost (28°F), last in spring, 50% chance after
April 18
Hard frost (28°F), first in fall, 50% chance before
October 20

The last 15 years (2006–2020 normals)

Typical last frost May 2 (2 days later than the 30-year normal), typical first fall frost October 13 (3 days later). Frost-free season 163 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 Lamar: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 13, 20% May 8, 30% May 5, 40% May 2, 50% April 30, 60% April 28, 70% April 25, 80% April 21, 90% April 17. Observed last spring frost in recent years: 2021 April 25, 2022 April 17, 2023 April 29, 2024 May 8, 2025 April 21, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1May 13Apr 30Apr 172021: April 252022: April 172023: April 292024: May 82025: April 212026: May 7Fall at Lamar: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 4, 30% October 6, 40% October 8, 50% October 10, 60% October 13, 70% October 16, 80% October 18, 90% October 21. Observed first fall frost in recent years: 2021 October 13, 2022 October 13, 2023 October 7, 2024 October 31, 2025 October 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 10Oct 212021: October 132022: October 132023: October 72024: October 312025: 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 25October 13
2022April 17October 13
2023April 29October 7
2024May 8October 31
2025April 21October 19
2026May 7season not over yet

What these dates mean

May 13 is the cautious spring light-frost date in Lamar; with only a 10 % chance that a frost will occur later, a gardener can plan to set out tender crops after this day. The parallel cautious fall date is October 1, when there is only a 10 % chance that a frost has arrived earlier, allowing harvests of tender crops to be finished safely.

April 30 is the 50% light-frost date for spring, indicating a 50 % chance of a frost later than this date, while October 10 is the 50% light-frost date for fall, indicating a 50 % chance of a frost earlier than this date. The 50% hard-frost dates are April 18 and October 20; a hard frost (28 °F) can damage plant tissue more severely than a light frost (32 °F), so those dates help gauge the higher-risk period.

How to read the probabilities

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

  • Spring: "10% after May 13" 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 Lamar, CONumbered nearest stations: 1 — Eads, CO — 28 mi; 2 — Las Animas, CO — 32 mi; 3 — La Junta, CO — 48 mi; 4 — Walsh, CO — 52 mi; 5 — Tribune, KS — 53 mi.COKS25 mi · 40 km1. Eads, CO — 28 mi12. Las Animas, CO — 32 mi23. La Junta, CO — 48 mi34. Walsh, CO — 52 mi45. Tribune, KS — 53 mi5
  1. Eads, CO 28 mi (44 km)
  2. Las Animas, CO 32 mi (51 km)
  3. La Junta, CO 48 mi (77 km)
  4. Walsh, CO 52 mi (84 km)
  5. Tribune, KS 53 mi (86 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: 38.0936, -102.6306.