U.S. Frost Dates by Weather Station

NOAA station USC00054945 · Colorado

Frost Dates for Leroy, CO

NOAA weather station Leroy 5 WSW (USC00054945), Colorado · elevation 4467 ft (1362 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 22only 1 spring in 10 still has a frost later
  • Typical last frostMay 1050% chance of a frost after it
  • Typical first fall frostOctober 650% chance of a frost before it
  • Frost-free season147 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Leroy, COSpring: a frost after April 28 in 9 years out of 10, after May 10 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 6 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 147 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 10First frost ~Oct 6Frost season at Leroy, COSpring: a frost after April 28 in 9 years out of 10, after May 10 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 6 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 147 days.JFMAMJJASONDLast frost ~May 10First frost ~Oct 6
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 22September 22
50% (typical)May 10October 6
90% (likely)April 28October 18
Frost-free season (32°F, 50% chance)
147 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 10 (same as the 30-year normal), typical first fall frost October 8 (2 days later). Frost-free season 149 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 Leroy: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 17, 30% May 15, 40% May 12, 50% May 10, 60% May 7, 70% May 5, 80% May 2, 90% April 28. Observed last spring frost in recent years: 2021 April 25, 2022 May 4, 2023 May 2, 2024 May 4, 2025 April 29, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 10Apr 282021: April 252022: May 42023: May 22024: May 42025: April 292026: May 7Fall at Leroy: chance of a frost before this dateFall, chance of a frost before the date: 10% September 22, 20% September 27, 30% September 30, 40% October 3, 50% October 6, 60% October 8, 70% October 11, 80% October 14, 90% October 18. Observed first fall frost in recent years: 2021 October 14, 2022 October 12, 2023 October 14, 2024 October 16, 2025 October 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 22Oct 6Oct 182021: October 142022: October 122023: 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 25October 14
2022May 4October 12
2023May 2October 14
2024May 4October 16
2025April 29October 19
2026May 7season not over yet

What these dates mean

The 147 days between the 50% light-frost dates, May 10 and October 6, bracket the period in which a light frost is equally likely to occur later (spring) or earlier (fall). For a gardener in Leroy these median dates indicate when the odds of a 32°F frost are split, providing a reference point for timing activities. The cautious spring date for setting out tender crops is May 22, when there is only a 10% chance of a later frost, while the cautious fall date is September 22, when there is only a 10% chance that a frost has already arrived. A hard frost, with a 50% median on April 30 in spring and October 15 in fall, matters more than a light frost because the lower 28°F temperature can damage plant tissue that would survive a 32°F event.

How to read the probabilities

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

  • Spring: "10% after May 22" 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 22" 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 Leroy, CONumbered nearest stations: 1 — near Akron, CO — 26 mi; 2 — Akron Washington County Airport, CO — 27 mi; 3 — Yuma, CO — 31 mi; 4 — Holyoke, CO — 34 mi; 5 — Sedgwick, CO — 35 mi.CONEKSWY25 mi · 40 km1. near Akron, CO — 26 mi12. Akron Washington County Airport, CO — 27 mi23. Yuma, CO — 31 mi34. Holyoke, CO — 34 mi45. Sedgwick, CO — 35 mi5
  1. near Akron, CO 26 mi (42 km)
  2. Akron Washington County Airport, CO 27 mi (43 km)
  3. Yuma, CO 31 mi (49 km)
  4. Holyoke, CO 34 mi (55 km)
  5. Sedgwick, CO 35 mi (56 km)

Sources

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

Station coordinates: 40.5147, -102.9906.