U.S. Frost Dates by Weather Station

NOAA station USC00057515 · Colorado

Frost Dates for Sedgwick, CO

NOAA weather station Sedgwick 5 S (USC00057515), Colorado · elevation 3996 ft (1218 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 18only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 750% chance of a frost before it
  • Frost-free season152 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Sedgwick, COSpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 24 in 1 year out of 10, before October 7 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 152 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 7Frost season at Sedgwick, COSpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 24 in 1 year out of 10, before October 7 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 152 days.JFMAMJJASONDLast frost ~May 6First frost ~Oct 7
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)May 18September 24
50% (typical)May 6October 7
90% (likely)April 24October 19
Frost-free season (32°F, 50% chance)
152 days
Hard frost (28°F), last in spring, 50% chance after
April 27
Hard frost (28°F), first in fall, 50% chance before
October 16

The last 15 years (2006–2020 normals)

Typical last frost May 5 (1 day earlier than the 30-year normal), typical first fall frost October 11 (4 days later). Frost-free season 157 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 Sedgwick: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 18, 20% May 14, 30% May 11, 40% May 8, 50% May 6, 60% May 4, 70% May 2, 80% April 29, 90% April 24. Observed last spring frost in recent years: 2021 May 9, 2022 May 22, 2023 May 2, 2024 May 4, 2025 May 3, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 18May 6Apr 242021: May 92022: May 222023: May 22024: May 42025: May 32026: May 2Fall at Sedgwick: chance of a frost before this dateFall, chance of a frost before the date: 10% September 24, 20% September 29, 30% October 1, 40% October 4, 50% October 7, 60% October 10, 70% October 12, 80% October 15, 90% October 19. Observed first fall frost in recent years: 2021 October 14, 2022 October 17, 2023 October 7, 2024 October 31, 2025 October 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 24Oct 7Oct 192021: October 142022: October 172023: October 72024: October 312025: October 19
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 9October 14
2022May 22October 17
2023May 2October 7
2024May 4October 31
2025May 3October 19
2026May 2season not over yet

What these dates mean

September 24 is the cautious fall date in Sedgwick, carrying a 10 % chance that a light frost has arrived; it marks the point at which tender crops should be finished. A later date such as October 19 carries a 90 % chance of frost and therefore is a gamble for late-season crops.

In spring the cautious date for setting out tender crops is May 18, when the chance of a light frost later than that date is only 10 %. Planting on April 24 would be a gamble, because a frost later than that date occurs 90 % of the time. The 50 % date of May 6 represents the median point at which a light frost is equally likely to have occurred or not, and the 50 % date of October 7 serves the same purpose for the autumn season.

Hard-frost median dates are April 27 in spring and October 16 in fall; a hard frost at 28 °F can damage plant tissue that survives a light frost at 32 °F, making it a more critical threshold for gardeners.

How to read the probabilities

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

  • Spring: "10% after May 18" 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 24" 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 Sedgwick, CONumbered nearest stations: 1 — Lodgepole, NE — 21 mi; 2 — Holyoke, CO — 24 mi; 3 — Leroy, CO — 35 mi; 4 — Oshkosh, NE — 38 mi; 5 — Ogallala, NE — 45 mi.NE25 mi · 40 km1. Lodgepole, NE — 21 mi12. Holyoke, CO — 24 mi23. Leroy, CO — 35 mi34. Oshkosh, NE — 38 mi45. Ogallala, NE — 45 mi5
  1. Lodgepole, NE 21 mi (33 km)
  2. Holyoke, CO 24 mi (39 km)
  3. Leroy, CO 35 mi (56 km)
  4. Oshkosh, NE 38 mi (61 km)
  5. Ogallala, NE 45 mi (73 km)

Sources

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

Station coordinates: 40.8658, -102.5161.