U.S. Frost Dates by Weather Station

NOAA station USC00481840 · Wyoming

Frost Dates for Cody, WY

NOAA weather station Cody (USC00481840), Wyoming · elevation 5280 ft (1609 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 27only 1 spring in 10 still has a frost later
  • Typical last frostMay 1250% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season140 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Cody, WYSpring: a frost after April 27 in 9 years out of 10, after May 12 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 17 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 140 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 12First frost ~Oct 1Frost season at Cody, WYSpring: a frost after April 27 in 9 years out of 10, after May 12 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 17 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 140 days.JFMAMJJASONDLast frost ~May 12First frost ~Oct 1
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 27September 17
50% (typical)May 12October 1
90% (likely)April 27October 14
Frost-free season (32°F, 50% chance)
140 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 10

The last 15 years (2006–2020 normals)

Typical last frost May 9 (3 days earlier than the 30-year normal), typical first fall frost October 5 (4 days later). Frost-free season 148 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 Cody: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 27, 20% May 22, 30% May 18, 40% May 15, 50% May 12, 60% May 8, 70% May 5, 80% May 1, 90% April 27. Observed last spring frost in recent years: 2021 May 23, 2022 May 23, 2023 April 28, 2024 May 5, 2025 May 7, 2026 May 19.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 27May 12Apr 272021: May 232022: May 232023: April 282024: May 52025: May 72026: May 19Fall at Cody: chance of a frost before this dateFall, chance of a frost before the date: 10% September 17, 20% September 22, 30% September 25, 40% September 28, 50% October 1, 60% October 3, 70% October 5, 80% October 9, 90% October 14. Observed first fall frost in recent years: 2021 October 12, 2022 October 24, 2023 October 25, 2024 October 19, 2025 October 7.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 17Oct 1Oct 142021: October 122022: October 242023: October 252024: October 192025: October 7
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 23October 12
2022May 23October 24
2023April 28October 25
2024May 5October 19
2025May 7October 7
2026May 19season not over yet

What these dates mean

September 17 is the cautious date to finish harvesting tender crops, only a 10% chance a light frost has arrived earlier.

The 50% light-frost date in spring is May 12 and in fall is October 1; each marks the point where a light frost is equally likely to have occurred before or after. For a cautious planting plan, the spring cautious date is May 27 (10% chance of a later light frost) and the fall cautious date is September 17 (10% chance of an earlier light frost).

The 50% hard-frost dates are April 30 in spring and October 10 in fall, and a hard frost at 28 °F can damage or kill plants that survive a 32 °F light frost. The record spans 30 years and the interval between the two 32°F 50% dates is 140 days.

How to read the probabilities

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

  • Spring: "10% after May 27" 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 17" 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 Cody, WYNumbered nearest stations: 1 — Powell, WY — 26 mi; 2 — Emblem, WY — 36 mi; 3 — Deaver, WY — 37 mi; 4 — Lovell, WY — 42 mi; 5 — Basin, WY — 54 mi.WYMT25 mi · 40 km1. Powell, WY — 26 mi12. Emblem, WY — 36 mi23. Deaver, WY — 37 mi34. Lovell, WY — 42 mi45. Basin, WY — 54 mi5
  1. Powell, WY 26 mi (41 km)
  2. Emblem, WY 36 mi (57 km)
  3. Deaver, WY 37 mi (60 km)
  4. Lovell, WY 42 mi (67 km)
  5. Basin, WY 54 mi (87 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: 44.5022, -109.1111.