U.S. Frost Dates by Weather Station

NOAA station USC00426053 · Utah

Frost Dates for Natural Bridges National Monument, UT

NOAA weather station Natural Bridges National Monument (USC00426053), Utah · elevation 6508 ft (1984 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 27only 1 spring in 10 still has a frost later
  • Typical last frostMay 550% chance of a frost after it
  • Typical first fall frostOctober 1350% chance of a frost before it
  • Frost-free season157 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Natural Bridges National Monument, UTSpring: a frost after April 22 in 9 years out of 10, after May 5 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 29 in 1 year out of 10, before October 13 in half of the years, before October 27 in 9 years out of 10. Typical frost-free season: 157 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 5First frost ~Oct 13Frost season at Natural Bridges National Monument, UTSpring: a frost after April 22 in 9 years out of 10, after May 5 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 29 in 1 year out of 10, before October 13 in half of the years, before October 27 in 9 years out of 10. Typical frost-free season: 157 days.JFMAMJJASONDLast frost ~May 5First 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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 27September 29
50% (typical)May 5October 13
90% (likely)April 22October 27
Frost-free season (32°F, 50% chance)
157 days
Hard frost (28°F), last in spring, 50% chance after
April 24
Hard frost (28°F), first in fall, 50% chance before
October 23

The last 15 years (2006–2020 normals)

Typical last frost May 9 (4 days later than the 30-year normal), typical first fall frost October 11 (2 days earlier). 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 Natural Bridges National Monument: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 27, 20% May 19, 30% May 13, 40% May 9, 50% May 5, 60% May 2, 70% April 30, 80% April 26, 90% April 22. Observed last spring frost in recent years: 2021 April 20, 2022 May 4, 2023 May 5, 2024 May 10, 2025 May 22, 2026 April 28.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 27May 5Apr 222021: April 202022: May 42023: May 52024: May 102025: May 222026: April 28Fall at Natural Bridges National Monument: chance of a frost before this dateFall, chance of a frost before the date: 10% September 29, 20% October 2, 30% October 6, 40% October 9, 50% October 13, 60% October 16, 70% October 19, 80% October 22, 90% October 27. Observed first fall frost in recent years: 2021 October 12, 2022 October 23, 2023 October 13, 2024 October 19, 2025 October 16.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 29Oct 13Oct 272021: October 122022: October 232023: October 132024: October 192025: October 16
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
2021April 20October 12
2022May 4October 23
2023May 5October 13
2024May 10October 19
2025May 22October 16
2026April 28season not over yet

What these dates mean

157 days separate the two 32°F 50% dates at Natural Bridges National Monument, marking the span within which tender crops can be grown under the most balanced frost odds. The 50% date of May 5 is the point where there is an equal chance of a light frost occurring later in spring, while the October 13 50% date is the point where there is an equal chance of a light frost occurring earlier in fall.

These dates are not frost thresholds themselves but simply the median odds markers for the 27-year record. For a cautious planting plan, the spring cautious date is May 27, the date with only a 10% chance of a later frost, and the fall cautious date is September 29, the date with only a 10% chance that a frost has already arrived.

A hard frost at 28°F, recorded by the median dates April 24 and October 23, can damage plants more severely than a light frost at 32°F because it occurs at a lower temperature.

How to read the probabilities

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

  • Spring: "10% after May 27" 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 29" 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 Natural Bridges National Monument, UTNumbered nearest stations: 1 — Blanding, UT — 27 mi; 2 — Bluff, UT — 32 mi; 3 — Canyonlands-The Needles, UT — 40 mi; 4 — Hans Flat Ranger Station, UT — 46 mi; 5 — Canyonlands-The Neck, UT — 59 mi.UTCO25 mi · 40 km1. Blanding, UT — 27 mi12. Bluff, UT — 32 mi23. Canyonlands-The Needles, UT — 40 mi34. Hans Flat Ranger Station, UT — 46 mi45. Canyonlands-The Neck, UT — 59 mi5
  1. Blanding, UT 27 mi (43 km)
  2. Bluff, UT 32 mi (52 km)
  3. Canyonlands-The Needles, UT 40 mi (65 km)
  4. Hans Flat Ranger Station, UT 46 mi (74 km)
  5. Canyonlands-The Neck, UT 59 mi (96 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: 37.6094, -109.9772.