U.S. Frost Dates by Weather Station

NOAA station USC00420788 · Utah

Frost Dates for Bluff, UT

NOAA weather station Bluff (USC00420788), Utah · elevation 4319 ft (1316 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 9only 1 spring in 10 still has a frost later
  • Typical last frostApril 2450% chance of a frost after it
  • Typical first fall frostOctober 1350% chance of a frost before it
  • Frost-free season172 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Bluff, UTSpring: a frost after April 8 in 9 years out of 10, after April 24 in half of the years, after May 9 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 13 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 172 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 24First frost ~Oct 13Frost season at Bluff, UTSpring: a frost after April 8 in 9 years out of 10, after April 24 in half of the years, after May 9 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 13 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 172 days.JFMAMJJASONDLast frost ~Apr 24First frost ~Oct 13
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 9October 1
50% (typical)April 24October 13
90% (likely)April 8October 28
Frost-free season (32°F, 50% chance)
172 days
Hard frost (28°F), last in spring, 50% chance after
April 9
Hard frost (28°F), first in fall, 50% chance before
October 23

The last 15 years (2006–2020 normals)

Typical last frost April 25 (1 day later than the 30-year normal), typical first fall frost October 12 (1 day earlier). Frost-free season 169 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 Bluff: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 9, 20% May 3, 30% April 30, 40% April 26, 50% April 24, 60% April 20, 70% April 17, 80% April 13, 90% April 8. Observed last spring frost in recent years: 2021 May 5, 2022 April 25, 2023 April 21, 2024 April 11, 2025 April 20, 2026 April 24.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 9Apr 24Apr 82021: May 52022: April 252023: April 212024: April 112025: April 202026: April 24Fall at Bluff: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 4, 30% October 7, 40% October 10, 50% October 13, 60% October 16, 70% October 19, 80% October 23, 90% October 28. Observed first fall frost in recent years: 2021 October 15, 2022 October 25, 2023 October 13, 2024 October 31, 2025 October 29.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 13Oct 282021: October 152022: October 252023: October 132024: October 312025: October 29
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 5October 15
2022April 25October 25
2023April 21October 13
2024April 11October 31
2025April 20October 29
2026April 24season not over yet

What these dates mean

May 9 is the cautious spring date for setting out tender crops, giving a gardener confidence that only a 10% chance of a light frost remains. The 50% light-frost dates—April 24 in spring and October 13 in fall—mark the point at which a light frost is equally likely to have occurred or not, so they serve as a midpoint of risk. October 1 is the cautious fall date for finishing harvest of tender crops, with only a 10% chance that a light frost has already arrived. A hard frost at 28 °F, indicated by the median dates April 9 and October 23, can damage plants that survive a light frost, making it a greater threat. The interval between the two 32 °F 50% dates spans 172 days, based on 25 years of record.

How to read the probabilities

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

  • Spring: "10% after May 9" 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 October 1" 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 Bluff, UTNumbered nearest stations: 1 — Blanding, UT — 23 mi; 2 — Natural Bridges National Monument, UT — 32 mi; 3 — Cortez, CO — 53 mi; 4 — Canyonlands-The Needles, UT — 62 mi; 5 — Betatakin, AZ — 69 mi.COAZNM50 mi · 80 km1. Blanding, UT — 23 mi12. Natural Bridges National Monument, UT — 32 mi23. Cortez, CO — 53 mi34. Canyonlands-The Needles, UT — 62 mi45. Betatakin, AZ — 69 mi5
  1. Blanding, UT 23 mi (37 km)
  2. Natural Bridges National Monument, UT 32 mi (52 km)
  3. Cortez, CO 53 mi (85 km)
  4. Canyonlands-The Needles, UT 62 mi (100 km)
  5. Betatakin, AZ 69 mi (110 km)

Sources

* Hardiness zone 7a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 37.2825, -109.5575.