U.S. Frost Dates by Weather Station

NOAA station USC00054664 · Colorado

Frost Dates for Kremmling, CO

NOAA weather station Kremmling (USC00054664), Colorado · elevation 7460 ft (2274 m) · hardiness zone 4a*

  • Lower-risk planting dateafter June 30only 1 spring in 10 still has a frost later
  • Typical last frostJune 1450% chance of a frost after it
  • Typical first fall frostSeptember 550% chance of a frost before it
  • Frost-free season80 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Kremmling, COSpring: a frost after June 1 in 9 years out of 10, after June 14 in half of the years, after June 30 in 1 year out of 10. Fall: the first frost comes before August 26 in 1 year out of 10, before September 5 in half of the years, before September 16 in 9 years out of 10. Typical frost-free season: 80 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 14First frost ~Sep 5Frost season at Kremmling, COSpring: a frost after June 1 in 9 years out of 10, after June 14 in half of the years, after June 30 in 1 year out of 10. Fall: the first frost comes before August 26 in 1 year out of 10, before September 5 in half of the years, before September 16 in 9 years out of 10. Typical frost-free season: 80 days.JFMAMJJASONDLast frost ~Jun 14First frost ~Sep 5
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)June 30August 26
50% (typical)June 14September 5
90% (likely)June 1September 16
Frost-free season (32°F, 50% chance)
80 days
Hard frost (28°F), last in spring, 50% chance after
May 28
Hard frost (28°F), first in fall, 50% chance before
September 16

The last 15 years (2006–2020 normals)

Typical last frost June 12 (2 days earlier than the 30-year normal), typical first fall frost September 6 (1 day later). Frost-free season 87 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 Kremmling: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 30, 20% June 24, 30% June 21, 40% June 17, 50% June 14, 60% June 11, 70% June 8, 80% June 5, 90% June 1. Observed last spring frost in recent years: 2021 May 28, 2022 June 21, 2023 May 29.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jun 30Jun 14Jun 12021: May 282022: June 212023: May 29Fall at Kremmling: chance of a frost before this dateFall, chance of a frost before the date: 10% August 26, 20% August 30, 30% September 1, 40% September 3, 50% September 5, 60% September 8, 70% September 10, 80% September 13, 90% September 16. Observed first fall frost in recent years: 2021 September 16, 2022 September 10, 2023 September 8.Fall: first frostChance of a frost before this date10%50%90%Sep 1Aug 26Sep 5Sep 162021: September 162022: September 102023: September 8
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
2021May 28September 16
2022June 21September 10
2023May 29September 8
2024incomplete recordno data
2025no datano data
2026no dataseason not over yet

What these dates mean

The 80 days between the 32°F 50% dates of June 14 and September 5 in Kremmling mark the interval where a light frost is equally likely to have occurred or not, giving gardeners a clear window for most tender work.

In spring the cautious date for setting out tender crops is June 30, when there is only a 10% chance of a frost later; planting on June 1 carries a 90% chance of a later frost and is a gamble. In fall the cautious date to finish harvesting tender crops is August 26, with a 10% chance that a frost has arrived earlier, while aiming for September 16 involves a 90% chance that a frost has already occurred. The 50% hard-frost dates are May 28 in spring and September 16 in fall.

A hard frost at 28 °F can damage plant tissue that often survives a light frost at 32 °F.

How to read the probabilities

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

  • Spring: "10% after June 30" 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 Kremmling, CONumbered nearest stations: 1 — near Granby, CO — 28 mi; 2 — Georgetown, CO — 43 mi; 3 — Cabin Creek, CO — 45 mi; 4 — near Coal Creek, CO — 53 mi; 5 — Grant, CO — 55 mi.25 mi · 40 km1. near Granby, CO — 28 mi12. Georgetown, CO — 43 mi23. Cabin Creek, CO — 45 mi34. near Coal Creek, CO — 53 mi45. Grant, CO — 55 mi5
  1. near Granby, CO 28 mi (45 km)
  2. Georgetown, CO 43 mi (69 km)
  3. Cabin Creek, CO 45 mi (72 km)
  4. near Coal Creek, CO 53 mi (86 km)
  5. Grant, CO 55 mi (89 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: 40.0575, -106.3681.