U.S. Frost Dates by Weather Station

NOAA station USC00053867 · Colorado

Frost Dates for Hayden, CO

NOAA weather station Hayden (USC00053867), Colorado · elevation 6467 ft (1971 m) · hardiness zone 5a*

  • Lower-risk planting dateafter June 16only 1 spring in 10 still has a frost later
  • Typical last frostJune 150% chance of a frost after it
  • Typical first fall frostSeptember 2050% chance of a frost before it
  • Frost-free season109 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Hayden, COSpring: a frost after May 15 in 9 years out of 10, after June 1 in half of the years, after June 16 in 1 year out of 10. Fall: the first frost comes before September 7 in 1 year out of 10, before September 20 in half of the years, before September 30 in 9 years out of 10. Typical frost-free season: 109 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 1First frost ~Sep 20Frost season at Hayden, COSpring: a frost after May 15 in 9 years out of 10, after June 1 in half of the years, after June 16 in 1 year out of 10. Fall: the first frost comes before September 7 in 1 year out of 10, before September 20 in half of the years, before September 30 in 9 years out of 10. Typical frost-free season: 109 days.JFMAMJJASONDLast frost ~Jun 1First frost ~Sep 20
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)June 16September 7
50% (typical)June 1September 20
90% (likely)May 15September 30
Frost-free season (32°F, 50% chance)
109 days
Hard frost (28°F), last in spring, 50% chance after
May 13
Hard frost (28°F), first in fall, 50% chance before
September 29

The last 15 years (2006–2020 normals)

Typical last frost June 1 (same as the 30-year normal), typical first fall frost September 21 (1 day later). Frost-free season 113 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 Hayden: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 16, 20% June 11, 30% June 7, 40% June 3, 50% June 1, 60% May 28, 70% May 25, 80% May 20, 90% May 15. Observed last spring frost in recent years: 2021 June 11, 2022 June 1, 2023 April 29, 2024 May 24, 2025 May 16, 2026 May 22.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 16Jun 1May 152021: June 112022: June 12023: April 292024: May 242025: May 162026: May 22Fall at Hayden: chance of a frost before this dateFall, chance of a frost before the date: 10% September 7, 20% September 11, 30% September 14, 40% September 17, 50% September 20, 60% September 22, 70% September 25, 80% September 27, 90% September 30. Observed first fall frost in recent years: 2021 September 21, 2022 October 11, 2023 September 23, 2024 October 18, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 7Sep 20Sep 302021: September 212022: October 112023: September 232024: October 182025: October 6
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 11September 21
2022June 1October 11
2023April 29September 23
2024May 24October 18
2025May 16October 6
2026May 22season not over yet

What these dates mean

Setting out tender crops on the early spring date of May 15 in Hayden carries a 90% chance of a frost later that season, so it is a gamble for any planting schedule. By contrast, the cautious spring date of June 16 reduces that risk to a 10% chance of a later frost.

The 50% spring date of June 1 marks the point where a frost is equally likely to occur after or before that day, and the 50% fall date of September 20 marks the point where a frost is equally likely to have arrived earlier or not yet arrived. For a low-risk plan, tender crops should be placed out after the cautious spring date of June 16 and harvested before the cautious fall date of September 7, each of which holds only a 10% chance of a frost.

Hard frost at 28 °F, recorded by the median dates of May 13 in spring and September 29 in fall, can damage plants more severely than a light 32 °F frost.

How to read the probabilities

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

  • Spring: "10% after June 16" 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 7" 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 Hayden, CONumbered nearest stations: 1 — Baggs, WY — 43 mi; 2 — Maybell, CO — 44 mi; 3 — Meeker, CO — 47 mi; 4 — Kremmling, CO — 56 mi; 5 — near Granby, CO — 76 mi.COWY25 mi · 40 km1. Baggs, WY — 43 mi12. Maybell, CO — 44 mi23. Meeker, CO — 47 mi34. Kremmling, CO — 56 mi45. near Granby, CO — 76 mi5
  1. Baggs, WY 43 mi (70 km)
  2. Maybell, CO 44 mi (71 km)
  3. Meeker, CO 47 mi (75 km)
  4. Kremmling, CO 56 mi (89 km)
  5. near Granby, CO 76 mi (123 km)

Sources

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

Station coordinates: 40.4925, -107.2547.