U.S. Frost Dates by Weather Station

NOAA station USC00429165 · Utah

Frost Dates near Silver Summit, UT

NOAA weather station Wanship Dam (USC00429165), Utah · elevation 5940 ft (1811 m) · hardiness zone 5b*

Silver Summit is the nearest town to the station (5.4 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter June 30only 1 spring in 10 still has a frost later
  • Typical last frostJune 1150% chance of a frost after it
  • Typical first fall frostSeptember 1250% chance of a frost before it
  • Frost-free season92 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season near Silver Summit, UTSpring: a frost after May 21 in 9 years out of 10, after June 11 in half of the years, after June 30 in 1 year out of 10. Fall: the first frost comes before August 28 in 1 year out of 10, before September 12 in half of the years, before September 27 in 9 years out of 10. Typical frost-free season: 92 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 11First frost ~Sep 12Frost season near Silver Summit, UTSpring: a frost after May 21 in 9 years out of 10, after June 11 in half of the years, after June 30 in 1 year out of 10. Fall: the first frost comes before August 28 in 1 year out of 10, before September 12 in half of the years, before September 27 in 9 years out of 10. Typical frost-free season: 92 days.JFMAMJJASONDLast frost ~Jun 11First frost ~Sep 12
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)June 30August 28
50% (typical)June 11September 12
90% (likely)May 21September 27
Frost-free season (32°F, 50% chance)
92 days
Hard frost (28°F), last in spring, 50% chance after
May 26
Hard frost (28°F), first in fall, 50% chance before
September 23

The last 15 years (2006–2020 normals)

Typical last frost June 9 (2 days earlier than the 30-year normal), typical first fall frost September 15 (3 days later). Frost-free season 98 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 near Silver Summit: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 30, 20% June 24, 30% June 20, 40% June 15, 50% June 11, 60% June 7, 70% June 2, 80% May 29, 90% May 21. Observed last spring frost in recent years: 2021 June 12, 2022 June 16, 2023 May 29, 2024 June 18, 2025 June 5, 2026 June 12.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jun 30Jun 11May 212021: June 122022: June 162023: May 292024: June 182025: June 52026: June 12Fall near Silver Summit: chance of a frost before this dateFall, chance of a frost before the date: 10% August 28, 20% September 2, 30% September 6, 40% September 9, 50% September 12, 60% September 15, 70% September 19, 80% September 22, 90% September 27. Observed first fall frost in recent years: 2021 September 20, 2022 September 11, 2023 September 24, 2024 September 19, 2025 September 23.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Aug 28Sep 12Sep 272021: September 202022: September 112023: September 242024: September 192025: September 23
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 12September 20
2022June 16September 11
2023May 29September 24
2024June 18September 19
2025June 5September 23
2026June 12season not over yet

What these dates mean

August 28 is the cautious fall date for finishing the harvest of tender crops in the Silver Summit area; there is only a 10 % chance that a light frost has arrived earlier.

The 50% light-frost date in fall is September 12, marking an even-odds point for a frost occurring earlier, while the 50% light-frost date in spring is June 11, indicating an even-odds point for a frost occurring later.

June 30 is the cautious spring date for setting out tender crops, with a 10 % chance of a frost later than that date. A hard frost at 28 °F can damage plants more severely than a light frost at 32 °F, so the median hard-frost dates of May 26 (spring) and September 23 (fall) are generally useful reference points.

How to read the probabilities

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

  • Spring: "10% after June 30" 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 August 28" 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 Silver Summit, UTNumbered nearest stations: 1 — Kamas, UT — 12 mi; 2 — near Coalville, UT — 12 mi; 3 — Alta, UT — 18 mi; 4 — Cottonwood Weir, UT — 23 mi; 5 — near Bountiful, UT — 24 mi.WY25 mi · 40 km1. Kamas, UT — 12 mi12. near Coalville, UT — 12 mi23. Alta, UT — 18 mi34. Cottonwood Weir, UT — 23 mi45. near Bountiful, UT — 24 mi5
  1. Kamas, UT 12 mi (19 km)
  2. near Coalville, UT 12 mi (20 km)
  3. Alta, UT 18 mi (29 km)
  4. Cottonwood Weir, UT 23 mi (37 km)
  5. near Bountiful, UT 24 mi (39 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: 40.7908, -111.4078.