U.S. Frost Dates by Weather Station

NOAA station USC00055446 · Colorado

Frost Dates for Maybell, CO

NOAA weather station Maybell (USC00055446), Colorado · elevation 5944 ft (1812 m) · hardiness zone 4a*

  • Lower-risk planting dateafter July 1only 1 spring in 10 still has a frost later
  • Typical last frostJune 1650% chance of a frost after it
  • Typical first fall frostSeptember 950% chance of a frost before it
  • Frost-free season83 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Maybell, COSpring: a frost after May 31 in 9 years out of 10, after June 16 in half of the years, after July 1 in 1 year out of 10. Fall: the first frost comes before August 26 in 1 year out of 10, before September 9 in half of the years, before September 22 in 9 years out of 10. Typical frost-free season: 83 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 16First frost ~Sep 9Frost season at Maybell, COSpring: a frost after May 31 in 9 years out of 10, after June 16 in half of the years, after July 1 in 1 year out of 10. Fall: the first frost comes before August 26 in 1 year out of 10, before September 9 in half of the years, before September 22 in 9 years out of 10. Typical frost-free season: 83 days.JFMAMJJASONDLast frost ~Jun 16First 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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)July 1August 26
50% (typical)June 16September 9
90% (likely)May 31September 22
Frost-free season (32°F, 50% chance)
83 days
Hard frost (28°F), last in spring, 50% chance after
June 1
Hard frost (28°F), first in fall, 50% chance before
September 19

The last 15 years (2006–2020 normals)

Typical last frost June 13 (3 days earlier than the 30-year normal), typical first fall frost September 9. Frost-free season 88 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 Maybell: chance of a frost after this dateSpring, chance of a frost after the date: 10% July 1, 20% June 26, 30% June 22, 40% June 19, 50% June 16, 60% June 13, 70% June 9, 80% June 6, 90% May 31. Observed last spring frost in recent years: 2021 June 12, 2022 June 21, 2023 June 24, 2024 June 1, 2025 June 23, 2026 June 12.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jul 1Jun 16May 312021: June 122022: June 212023: June 242024: June 12025: June 232026: June 12Fall at Maybell: chance of a frost before this dateFall, chance of a frost before the date: 10% August 26, 20% September 1, 30% September 3, 40% September 6, 50% September 9, 60% September 12, 70% September 14, 80% September 17, 90% September 22. Observed first fall frost in recent years: 2021 September 5, 2022 September 11, 2023 September 12, 2024 August 30, 2025 August 10.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Aug 26Sep 9Sep 222021: September 52022: September 112023: September 122024: August 302025: August 10
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 5
2022June 21September 11
2023June 24September 12
2024June 1August 30
2025June 23August 10
2026June 12season not over yet

What these dates mean

Setting out tender crops on the early spring date of May 31 carries a 90% chance of a light frost, making it a gamble for growers in Maybell. The cautious spring date is July 1, when the chance of a frost drops to 10%.

June 16 is the 50% light-frost date, meaning there is a 50% chance of a frost later than this date; September 9 is the 50% light-frost date, meaning there is a 50% chance of a frost earlier than this date. The hard-frost 50% dates are June 1 and September 19, and a hard frost matters more because temperatures of 28 °F can damage plants more severely than a light frost at 32 °F.

In the fall the cautious date to finish harvesting tender crops is August 26, with only a 10% chance that frost has arrived earlier, while planting or holding tender crops until September 22 is a gamble, as that date carries a 90% chance of a frost.

How to read the probabilities

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

  • Spring: "10% after July 1" 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 26" 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 Maybell, CONumbered nearest stations: 1 — Meeker, CO — 35 mi; 2 — Baggs, WY — 43 mi; 3 — Hayden, CO — 44 mi; 4 — Rangely, CO — 46 mi; 5 — Jensen, UT — 67 mi.UTWY25 mi · 40 km1. Meeker, CO — 35 mi12. Baggs, WY — 43 mi23. Hayden, CO — 44 mi34. Rangely, CO — 46 mi45. Jensen, UT — 67 mi5
  1. Meeker, CO 35 mi (56 km)
  2. Baggs, WY 43 mi (69 km)
  3. Hayden, CO 44 mi (71 km)
  4. Rangely, CO 46 mi (75 km)
  5. Jensen, UT 67 mi (107 km)

Sources

* Hardiness zone 4a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.5158, -108.0947.