U.S. Frost Dates by Weather Station

NOAA station USC00050454 · Colorado

Frost Dates for Bailey, CO

NOAA weather station Bailey (USC00050454), Colorado · elevation 7752 ft (2363 m) · hardiness zone 5a*

  • 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 850% chance of a frost before it
  • Frost-free season84 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Bailey, COSpring: a frost after June 2 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 27 in 1 year out of 10, before September 8 in half of the years, before September 20 in 9 years out of 10. Typical frost-free season: 84 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 16First frost ~Sep 8Frost season at Bailey, COSpring: a frost after June 2 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 27 in 1 year out of 10, before September 8 in half of the years, before September 20 in 9 years out of 10. Typical frost-free season: 84 days.JFMAMJJASONDLast frost ~Jun 16First frost ~Sep 8
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 27
50% (typical)June 16September 8
90% (likely)June 2September 20
Frost-free season (32°F, 50% chance)
84 days
Hard frost (28°F), last in spring, 50% chance after
May 30
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 (1 day later). Frost-free season 89 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 Bailey: chance of a frost after this dateSpring, chance of a frost after the date: 10% July 1, 20% June 27, 30% June 22, 40% June 20, 50% June 16, 60% June 13, 70% June 11, 80% June 7, 90% June 2. Observed last spring frost in recent years: 2021 June 2.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jul 1Jun 16Jun 22021: June 2Fall at Bailey: chance of a frost before this dateFall, chance of a frost before the date: 10% August 27, 20% September 1, 30% September 3, 40% September 6, 50% September 8, 60% September 11, 70% September 14, 80% September 16, 90% September 20. Observed first fall frost in recent years: 2021 September 5.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Aug 27Sep 8Sep 202021: September 5
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 2September 5
2022incomplete recordno data
2023no datano data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

July 1 is the cautious spring date in Bailey; with only a 10 % chance of a light frost after that day, gardeners can plan to set out tender crops with confidence. The median point for spring light-frost risk is June 16, which marks a 50 % chance of a frost later than this date, while the 90 % chance on June 2 signals a gamble for early planting.

In the fall, August 27 serves as the cautious date to finish harvesting tender crops, because there is just a 10 % chance of a light frost before it. The median fall date is September 8, indicating a 50 % chance of a frost earlier than this day, and the 90 % chance on September 20 warns that waiting longer is risky.

The hard-frost 28 °F median dates are May 30 in spring and September 19 in fall; a hard frost can damage plant tissue that survives a light frost, so it represents a higher threat to tender crops.

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 27" 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 Bailey, CONumbered nearest stations: 1 — Grant, CO — 11 mi; 2 — Evergreen, CO — 18 mi; 3 — Cabin Creek, CO — 21 mi; 4 — Georgetown, CO — 24 mi; 5 — Castle Rock, CO — 30 mi.25 mi · 40 km1. Grant, CO — 11 mi12. Evergreen, CO — 18 mi23. Cabin Creek, CO — 21 mi34. Georgetown, CO — 24 mi45. Castle Rock, CO — 30 mi5
  1. Grant, CO 11 mi (18 km)
  2. Evergreen, CO 18 mi (29 km)
  3. Cabin Creek, CO 21 mi (34 km)
  4. Georgetown, CO 24 mi (38 km)
  5. Castle Rock, CO 30 mi (49 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: 39.4053, -105.4764.