U.S. Frost Dates by Weather Station

NOAA station USC00059243 · Colorado

Frost Dates for Wray, CO

NOAA weather station Wray (USC00059243), Colorado · elevation 3553 ft (1083 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 19only 1 spring in 10 still has a frost later
  • Typical last frostMay 750% chance of a frost after it
  • Typical first fall frostOctober 650% chance of a frost before it
  • Frost-free season151 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Wray, COSpring: a frost after April 25 in 9 years out of 10, after May 7 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 25 in 1 year out of 10, before October 6 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 151 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 7First frost ~Oct 6Frost season at Wray, COSpring: a frost after April 25 in 9 years out of 10, after May 7 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 25 in 1 year out of 10, before October 6 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 151 days.JFMAMJJASONDLast frost ~May 7First frost ~Oct 6
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 19September 25
50% (typical)May 7October 6
90% (likely)April 25October 16
Frost-free season (32°F, 50% chance)
151 days
Hard frost (28°F), last in spring, 50% chance after
April 29
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 7 (same as the 30-year normal), typical first fall frost October 10 (4 days later). Frost-free season 153 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 Wray: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 19, 20% May 15, 30% May 12, 40% May 9, 50% May 7, 60% May 4, 70% May 2, 80% April 30, 90% April 25.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 19May 7Apr 25Fall at Wray: chance of a frost before this dateFall, chance of a frost before the date: 10% September 25, 20% September 29, 30% October 1, 40% October 4, 50% October 6, 60% October 8, 70% October 11, 80% October 13, 90% October 16.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 25Oct 6Oct 16
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.

What these dates mean

May 19 is the cautious spring light-frost date for Wray, with only a 10 % chance that a 32 °F frost will occur later; this lets a gardener schedule the first planting of tender crops with minimal risk. The 50 % light-frost date of May 7 means there is an even odds chance of a frost later than that day, while the hard-frost median of April 29 marks the point where a 28 °F frost is as likely as not.

The cautious fall light-frost date is September 25, when there is just a 10 % chance that a frost has already arrived, so harvest of tender crops can be wrapped up with confidence. The 50 % light-frost date of October 6 carries even odds of a frost earlier, and the hard-frost median of October 15 signals when a 28 °F freeze becomes as probable as a milder frost; hard frosts can damage plant tissue that survives a light frost.

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 25" 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 Wray, CONumbered nearest stations: 1 — Yuma, CO — 27 mi; 2 — Bonny Dam 2 NE, CO — 30 mi; 3 — Saint Francis, KS — 30 mi; 4 — Holyoke, CO — 33 mi; 5 — Benkelman, NE — 35 mi.NEKS25 mi · 40 km1. Yuma, CO — 27 mi12. Bonny Dam 2 NE, CO — 30 mi23. Saint Francis, KS — 30 mi34. Holyoke, CO — 33 mi45. Benkelman, NE — 35 mi5
  1. Yuma, CO 27 mi (44 km)
  2. Bonny Dam 2 NE, CO 30 mi (48 km)
  3. Saint Francis, KS 30 mi (49 km)
  4. Holyoke, CO 33 mi (53 km)
  5. Benkelman, NE 35 mi (56 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: 40.0819, -102.2069.