U.S. Frost Dates by Weather Station

NOAA station USC00424467 · Utah

Frost Dates for Kamas, UT

NOAA weather station Kamas (USC00424467), Utah · elevation 6481 ft (1975 m) · hardiness zone 5b*

  • Lower-risk planting dateafter June 23only 1 spring in 10 still has a frost later
  • Typical last frostJune 550% chance of a frost after it
  • Typical first fall frostSeptember 1750% chance of a frost before it
  • Frost-free season100 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Kamas, UTSpring: a frost after May 20 in 9 years out of 10, after June 5 in half of the years, after June 23 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 17 in half of the years, before October 1 in 9 years out of 10. Typical frost-free season: 100 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 5First frost ~Sep 17Frost season at Kamas, UTSpring: a frost after May 20 in 9 years out of 10, after June 5 in half of the years, after June 23 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 17 in half of the years, before October 1 in 9 years out of 10. Typical frost-free season: 100 days.JFMAMJJASONDLast frost ~Jun 5First frost ~Sep 17
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 23September 1
50% (typical)June 5September 17
90% (likely)May 20October 1
Frost-free season (32°F, 50% chance)
100 days
Hard frost (28°F), last in spring, 50% chance after
May 19
Hard frost (28°F), first in fall, 50% chance before
September 27

The last 15 years (2006–2020 normals)

Typical last frost June 6 (1 day later than the 30-year normal), typical first fall frost September 19 (2 days later). Frost-free season 104 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 Kamas: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 23, 20% June 17, 30% June 13, 40% June 9, 50% June 5, 60% June 2, 70% May 30, 80% May 25, 90% May 20. Observed last spring frost in recent years: 2021 June 11, 2022 June 15, 2023 May 9, 2024 June 18, 2025 May 20, 2026 June 11.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jun 23Jun 5May 202021: June 112022: June 152023: May 92024: June 182025: May 202026: June 11Fall at Kamas: chance of a frost before this dateFall, chance of a frost before the date: 10% September 1, 20% September 7, 30% September 11, 40% September 14, 50% September 17, 60% September 20, 70% September 23, 80% September 27, 90% October 1. Observed first fall frost in recent years: 2021 September 20, 2022 October 12, 2023 September 23, 2024 September 13, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 1Sep 17Oct 12021: September 202022: October 122023: September 232024: September 132025: October 6
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
2021June 11September 20
2022June 15October 12
2023May 9September 23
2024June 18September 13
2025May 20October 6
2026June 11season not over yet

What these dates mean

The 100 days between the 32°F 50% dates, June 5 and September 17, define the period in which tender crops can be grown at Kamas. The 50% date of June 5 indicates a 50% chance of a frost later than this date, while the 50% date of September 17 indicates a 50% chance of a frost earlier than this date. These dates are not frost dates themselves but indicate when the odds are split.

A cautious spring plan uses June 23, the date with only a 10 % chance of a frost later, for setting out tender crops. In fall, the cautious date is September 1, when there is only a 10 % chance that a frost has arrived earlier, making it the preferred day to finish harvesting tender crops. Hard frost at 28 °F is a greater threat than light frost at 32 °F because it can damage plant tissue that survives the milder temperature.

How to read the probabilities

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

  • Spring: "10% after June 23" 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 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 Kamas, UTNumbered nearest stations: 1 — near Silver Summit, UT — 12 mi; 2 — Alta, UT — 19 mi; 3 — near Midway, UT — 21 mi; 4 — near Coalville, UT — 24 mi; 5 — Cottonwood Weir, UT — 26 mi.WY25 mi · 40 km1. near Silver Summit, UT — 12 mi12. Alta, UT — 19 mi23. near Midway, UT — 21 mi34. near Coalville, UT — 24 mi45. Cottonwood Weir, UT — 26 mi5
  1. near Silver Summit, UT 12 mi (19 km)
  2. Alta, UT 19 mi (31 km)
  3. near Midway, UT 21 mi (34 km)
  4. near Coalville, UT 24 mi (38 km)
  5. Cottonwood Weir, UT 26 mi (42 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: 40.6439, -111.2822.