U.S. Frost Dates by Weather Station

NOAA station USC00425402 · Utah

Frost Dates for Manti, UT

NOAA weather station Manti (USC00425402), Utah · elevation 5740 ft (1750 m) · hardiness zone 6a*

  • Lower-risk planting dateafter June 1only 1 spring in 10 still has a frost later
  • Typical last frostMay 1150% chance of a frost after it
  • Typical first fall frostOctober 650% chance of a frost before it
  • Frost-free season146 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Manti, UTSpring: a frost after April 25 in 9 years out of 10, after May 11 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 24 in 1 year out of 10, before October 6 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 11First frost ~Oct 6Frost season at Manti, UTSpring: a frost after April 25 in 9 years out of 10, after May 11 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 24 in 1 year out of 10, before October 6 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 146 days.JFMAMJJASONDLast frost ~May 11First frost ~Oct 6
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)June 1September 24
50% (typical)May 11October 6
90% (likely)April 25October 19
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 26
Hard frost (28°F), first in fall, 50% chance before
October 16

The last 15 years (2006–2020 normals)

Typical last frost May 12 (1 day later than the 30-year normal), typical first fall frost October 4 (2 days earlier). Frost-free season 144 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 Manti: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 1, 20% May 25, 30% May 19, 40% May 15, 50% May 11, 60% May 7, 70% May 3, 80% April 30, 90% April 25. Observed last spring frost in recent years: 2021 May 23, 2022 May 31, 2023 May 6, 2024 May 24, 2025 May 20, 2026 May 19.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 1May 11Apr 252021: May 232022: May 312023: May 62024: May 242025: May 202026: May 19Fall at Manti: chance of a frost before this dateFall, chance of a frost before the date: 10% September 24, 20% September 28, 30% October 1, 40% October 3, 50% October 6, 60% October 9, 70% October 12, 80% October 16, 90% October 19. Observed first fall frost in recent years: 2021 October 11, 2022 October 23, 2023 October 13, 2024 October 18, 2025 October 7.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 24Oct 6Oct 192021: October 112022: October 232023: October 132024: October 182025: 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 11
2022May 31October 23
2023May 6October 13
2024May 24October 18
2025May 20October 7
2026May 19season not over yet

What these dates mean

The 146 days between the 32°F 50% dates in Manti frame the window when a light frost is equally likely to have occurred or not. The 50% date is May 11 in spring and the 50% date is October 6 in fall; these dates themselves are not frost dates.

The cautious date for setting out tender crops is June 1, which carries a 10 % chance of a light frost later, while planting on April 25 involves a 90 % chance and is a gamble. In the autumn, the cautious date to finish harvesting tender crops is September 24, with a 10 % chance of a light frost earlier, and October 19 represents a 90 % gamble. The 50% hard-frost dates are April 26 and October 16; a hard frost at 28 °F can damage or kill plants that survive a light frost, making it a more serious risk.

How to read the probabilities

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

  • Spring: "10% after June 1" 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 24" 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 Manti, UTNumbered nearest stations: 1 — Ephraim, UT — 7 mi; 2 — Salina, UT — 26 mi; 3 — Ferron, UT — 29 mi; 4 — Nephi, UT — 33 mi; 5 — Scofield-Skyline Mine, UT — 37 mi.25 mi · 40 km1. Ephraim, UT — 7 mi12. Salina, UT — 26 mi23. Ferron, UT — 29 mi34. Nephi, UT — 33 mi45. Scofield-Skyline Mine, UT — 37 mi5
  1. Ephraim, UT 7 mi (11 km)
  2. Salina, UT 26 mi (43 km)
  3. Ferron, UT 29 mi (47 km)
  4. Nephi, UT 33 mi (53 km)
  5. Scofield-Skyline Mine, UT 37 mi (60 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 39.2583, -111.6308.