U.S. Frost Dates by Weather Station

NOAA station USC00426568 · Utah

Frost Dates for Ouray, UT

NOAA weather station Ouray 4 NE (USC00426568), Utah · elevation 4674 ft (1425 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 16only 1 spring in 10 still has a frost later
  • Typical last frostMay 250% chance of a frost after it
  • Typical first fall frostOctober 350% chance of a frost before it
  • Frost-free season152 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Ouray, UTSpring: a frost after April 19 in 9 years out of 10, after May 2 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 152 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 2First frost ~Oct 3Frost season at Ouray, UTSpring: a frost after April 19 in 9 years out of 10, after May 2 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 152 days.JFMAMJJASONDLast frost ~May 2First frost ~Oct 3
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 16September 21
50% (typical)May 2October 3
90% (likely)April 19October 16
Frost-free season (32°F, 50% chance)
152 days
Hard frost (28°F), last in spring, 50% chance after
April 19
Hard frost (28°F), first in fall, 50% chance before
October 13

The last 15 years (2006–2020 normals)

Typical last frost May 2 (same as the 30-year normal), typical first fall frost October 5 (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 Ouray: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 16, 20% May 11, 30% May 7, 40% May 4, 50% May 2, 60% April 29, 70% April 27, 80% April 24, 90% April 19. Observed last spring frost in recent years: 2021 May 12, 2022 May 23, 2023 April 26.Spring: last frostChance of a frost after this date10%50%90%May 1May 16May 2Apr 192021: May 122022: May 232023: April 26Fall at Ouray: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 26, 30% September 28, 40% October 1, 50% October 3, 60% October 5, 70% October 7, 80% October 11, 90% October 16. Observed first fall frost in recent years: 2021 October 15, 2022 October 14, 2023 October 4.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 21Oct 3Oct 162021: October 152022: October 142023: October 4
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 12October 15
2022May 23October 14
2023April 26October 4
2024incomplete recordincomplete record
2025incomplete recordno data
2026no dataseason not over yet

What these dates mean

September 21 is the cautious fall date for finishing the harvest of tender crops in Ouray, because there is only a 10 % chance that a light frost has arrived earlier. In spring the cautious date for setting out tender crops is May 16, when a light frost later than that day occurs in only 10 % of years.

The 50 % dates are May 2 for spring and October 3 for fall, each indicating an even chance of a light frost on that day. The 50 % hard-frost dates are April 19 and October 13, showing where a 28 °F event is equally likely to have occurred or not. Hard frost matters more than light frost because temperatures of 28 °F can damage plants that would survive the milder 32 °F light frosts.

How to read the probabilities

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

  • Spring: "10% after May 16" 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 21" 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 Ouray, UTNumbered nearest stations: 1 — near Roosevelt, UT — 20 mi; 2 — Jensen, UT — 22 mi; 3 — Neola, UT — 29 mi; 4 — Duchesne, UT — 40 mi; 5 — Rangely, CO — 46 mi.CO25 mi · 40 km1. near Roosevelt, UT — 20 mi12. Jensen, UT — 22 mi23. Neola, UT — 29 mi34. Duchesne, UT — 40 mi45. Rangely, CO — 46 mi5
  1. near Roosevelt, UT 20 mi (32 km)
  2. Jensen, UT 22 mi (36 km)
  3. Neola, UT 29 mi (47 km)
  4. Duchesne, UT 40 mi (64 km)
  5. Rangely, CO 46 mi (74 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: 40.1344, -109.6436.