U.S. Frost Dates by Weather Station

NOAA station USC00026616 · Arizona

Frost Dates for Pipe Spring National Monument, AZ

NOAA weather station Pipe Spring National Monument (USC00026616), Arizona · elevation 4920 ft (1500 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 18only 1 spring in 10 still has a frost later
  • Typical last frostMay 150% chance of a frost after it
  • Typical first fall frostOctober 1950% chance of a frost before it
  • Frost-free season168 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Pipe Spring National Monument, AZSpring: a frost after April 17 in 9 years out of 10, after May 1 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 19 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 168 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 1First frost ~Oct 19Frost season at Pipe Spring National Monument, AZSpring: a frost after April 17 in 9 years out of 10, after May 1 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 19 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 168 days.JFMAMJJASONDLast frost ~May 1First frost ~Oct 19
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 18October 5
50% (typical)May 1October 19
90% (likely)April 17November 1
Frost-free season (32°F, 50% chance)
168 days
Hard frost (28°F), last in spring, 50% chance after
April 18
Hard frost (28°F), first in fall, 50% chance before
October 29

The last 15 years (2006–2020 normals)

Typical last frost May 1 (same as the 30-year normal), typical first fall frost October 17 (2 days earlier). Frost-free season 168 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 Pipe Spring National Monument: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 18, 20% May 13, 30% May 8, 40% May 4, 50% May 1, 60% April 28, 70% April 25, 80% April 22, 90% April 17. Observed last spring frost in recent years: 2021 May 23, 2022 April 24, 2023 May 9.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 18May 1Apr 172021: May 232022: April 242023: May 9Fall at Pipe Spring National Monument: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 9, 30% October 13, 40% October 16, 50% October 19, 60% October 22, 70% October 24, 80% October 27, 90% November 1. Observed first fall frost in recent years: 2021 October 12, 2024 October 30.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 19Nov 12021: October 122024: October 30
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 12
2022April 24incomplete record
2023May 9incomplete record
2024incomplete recordOctober 30
2025incomplete recordincomplete record
2026incomplete recordseason not over yet

What these dates mean

The span between the two 32 °F 50 % dates is 168 days, providing the window in which most gardening activities occur at Pipe Spring National Monument. The 50 % date in spring is May 1, which marks the point at which the chance of a light frost later is 50 %, and the 50 % date in fall is October 19, which marks the point at which the chance of a light frost earlier is 50 %. A cautious plan uses the May 18 date, when only 10 % of springs see a frost later, for setting out tender crops, and the October 5 date, when only 10 % of falls see a frost earlier, for finishing harvest of tender crops.

A hard frost at 28 °F can damage plants that would survive a light frost at 32 °F, so the 28 °F threshold is more critical.

How to read the probabilities

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

  • Spring: "10% after May 18" 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 5" 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 Pipe Spring National Monument, AZNumbered nearest stations: 1 — Kanab, UT — 16 mi; 2 — Zion National Park, UT — 27 mi; 3 — Alton, UT — 42 mi; 4 — New Harmony, UT — 51 mi; 5 — Bryce Canyon National Park Headquarters, UT — 62 mi.UTNV25 mi · 40 km1. Kanab, UT — 16 mi12. Zion National Park, UT — 27 mi23. Alton, UT — 42 mi34. New Harmony, UT — 51 mi45. Bryce Canyon National Park Headquarters, UT — 62 mi5
  1. Kanab, UT 16 mi (26 km)
  2. Zion National Park, UT 27 mi (44 km)
  3. Alton, UT 42 mi (68 km)
  4. New Harmony, UT 51 mi (83 km)
  5. Bryce Canyon National Park Headquarters, UT 62 mi (100 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: 36.8625, -112.7375.