U.S. Frost Dates by Weather Station

NOAA station USC00054538 · Colorado

Frost Dates for Kim 15 NNE, CO

NOAA weather station Kim 15 NNE (USC00054538), Colorado · elevation 5190 ft (1582 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 19only 1 spring in 10 still has a frost later
  • Typical last frostMay 550% chance of a frost after it
  • Typical first fall frostOctober 950% chance of a frost before it
  • Frost-free season156 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Kim 15 NNE, COSpring: a frost after April 23 in 9 years out of 10, after May 5 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 9 in half of the years, before October 21 in 9 years out of 10. Typical frost-free season: 156 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 5First frost ~Oct 9Frost season at Kim 15 NNE, COSpring: a frost after April 23 in 9 years out of 10, after May 5 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 9 in half of the years, before October 21 in 9 years out of 10. Typical frost-free season: 156 days.JFMAMJJASONDLast frost ~May 5First frost ~Oct 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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 19September 27
50% (typical)May 5October 9
90% (likely)April 23October 21
Frost-free season (32°F, 50% chance)
156 days
Hard frost (28°F), last in spring, 50% chance after
April 27
Hard frost (28°F), first in fall, 50% chance before
October 17

The last 15 years (2006–2020 normals)

Typical last frost May 6 (1 day later than the 30-year normal), typical first fall frost October 11 (2 days later). Frost-free season 155 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 Kim 15 NNE: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 19, 20% May 14, 30% May 10, 40% May 8, 50% May 5, 60% May 3, 70% April 30, 80% April 28, 90% April 23. Observed last spring frost in recent years: 2021 May 4, 2022 May 4, 2023 April 29, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 19May 5Apr 232021: May 42022: May 42023: April 292026: May 7Fall at Kim 15 NNE: chance of a frost before this dateFall, chance of a frost before the date: 10% September 27, 20% October 1, 30% October 4, 40% October 6, 50% October 9, 60% October 11, 70% October 14, 80% October 17, 90% October 21. Observed first fall frost in recent years: 2021 October 14, 2022 October 17, 2023 October 14.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 27Oct 9Oct 212021: October 142022: October 172023: October 14
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 4October 14
2022May 4October 17
2023April 29October 14
2024incomplete recordno data
2025no dataincomplete record
2026May 7season not over yet

What these dates mean

May 19, the 10 % chance light-frost date, is the cautious spring date for setting out tender crops at Kim 15 NNE. With only a one-in-ten chance that a light frost will still occur after this day, a gardener can plan to move seedlings outdoors with relatively low risk.

The 50 % light-frost dates—May 5 in spring and October 9 in fall—mark the point where the odds of a frost later (spring) or earlier (fall) are equal. They are not frost dates but simply indicate a fifty-fifty chance, helping a gardener gauge the middle of the risk range.

In the autumn, September 27 serves as the cautious 10 % chance date for finishing harvest of tender crops because only a small chance exists that a light frost has already arrived. A hard frost, defined by 28 °F, matters more than a light frost because the lower temperature can cause more severe damage to plant tissue.

How to read the probabilities

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

  • Spring: "10% after May 19" 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 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 Kim 15 NNE, CONumbered nearest stations: 1 — Kim 10 SSE, CO — 23 mi; 2 — La Junta, CO — 42 mi; 3 — Las Animas, CO — 43 mi; 4 — Walsh, CO — 56 mi; 5 — near Trinidad, CO — 57 mi.CO25 mi · 40 km1. Kim 10 SSE, CO — 23 mi12. La Junta, CO — 42 mi23. Las Animas, CO — 43 mi34. Walsh, CO — 56 mi45. near Trinidad, CO — 57 mi5
  1. Kim 10 SSE, CO 23 mi (38 km)
  2. La Junta, CO 42 mi (68 km)
  3. Las Animas, CO 43 mi (68 km)
  4. Walsh, CO 56 mi (91 km)
  5. near Trinidad, CO 57 mi (92 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 37.4536, -103.3219.