U.S. Frost Dates by Weather Station

NOAA station USC00027855 · Arizona

Frost Dates for Show Low, AZ

NOAA weather station Show Low Airport (USC00027855), Arizona · elevation 6411 ft (1954 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 20only 1 spring in 10 still has a frost later
  • Typical last frostMay 550% chance of a frost after it
  • Typical first fall frostOctober 1550% chance of a frost before it
  • Frost-free season162 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Show Low, AZSpring: a frost after April 21 in 9 years out of 10, after May 5 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before October 2 in 1 year out of 10, before October 15 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 162 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 5First frost ~Oct 15Frost season at Show Low, AZSpring: a frost after April 21 in 9 years out of 10, after May 5 in half of the years, after May 20 in 1 year out of 10. Fall: the first frost comes before October 2 in 1 year out of 10, before October 15 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 162 days.JFMAMJJASONDLast frost ~May 5First frost ~Oct 15
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 20October 2
50% (typical)May 5October 15
90% (likely)April 21October 28
Frost-free season (32°F, 50% chance)
162 days
Hard frost (28°F), last in spring, 50% chance after
April 22
Hard frost (28°F), first in fall, 50% chance before
October 24

The last 15 years (2006–2020 normals)

Typical last frost May 7 (2 days later than the 30-year normal), typical first fall frost October 13 (2 days earlier). Frost-free season 159 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 Show Low: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 20, 20% May 14, 30% May 10, 40% May 7, 50% May 5, 60% May 2, 70% April 30, 80% April 25, 90% April 21. Observed last spring frost in recent years: 2021 May 23, 2022 April 25, 2023 April 26, 2024 April 16, 2025 May 20, 2026 April 28.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 20May 5Apr 212021: May 232022: April 252023: April 262024: April 162025: May 202026: April 28Fall at Show Low: chance of a frost before this dateFall, chance of a frost before the date: 10% October 2, 20% October 6, 30% October 9, 40% October 12, 50% October 15, 60% October 17, 70% October 20, 80% October 23, 90% October 28. Observed first fall frost in recent years: 2021 October 12, 2022 October 24, 2023 October 13, 2024 October 19, 2025 October 25.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 2Oct 15Oct 282021: October 122022: October 242023: October 132024: October 192025: October 25
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 25October 24
2023April 26October 13
2024April 16October 19
2025May 20October 25
2026April 28season not over yet

What these dates mean

Setting out tender crops on the early spring date of April 21 in Show Low carries a 90 % chance of a light frost later than this date. The cautious alternative is May 20, when only a 10 % chance of a later light frost remains. The median point for light-frost risk is the 50 % date of May 5, at which the chance of a later frost is even.

In the fall, finishing tender-crop harvests by the cautious date of October 2 leaves just a 10 % chance that a light frost has already arrived, while waiting until October 28 makes the effort a gamble with a 90 % chance of an earlier frost. The 50 % date of October 15 marks the even-odds point for an earlier frost. Hard-frost risk is shown by the 50 % dates of April 22 in spring and October 24 in fall.

Because a hard frost at 28 °F can damage plants more severely than a light frost at 32 °F, it represents a higher threat to tender crops.

How to read the probabilities

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

  • Spring: "10% after May 20" 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 2" 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 Show Low, AZNumbered nearest stations: 1 — McNary, AZ — 13 mi; 2 — Petrified Forest National Park, AZ — 38 mi; 3 — Saint Johns, AZ — 39 mi; 4 — Springerville, AZ — 43 mi; 5 — Winslow, AZ — 67 mi.AZNM25 mi · 40 km1. McNary, AZ — 13 mi12. Petrified Forest National Park, AZ — 38 mi23. Saint Johns, AZ — 39 mi34. Springerville, AZ — 43 mi45. Winslow, AZ — 67 mi5
  1. McNary, AZ 13 mi (22 km)
  2. Petrified Forest National Park, AZ 38 mi (61 km)
  3. Saint Johns, AZ 39 mi (62 km)
  4. Springerville, AZ 43 mi (69 km)
  5. Winslow, AZ 67 mi (107 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: 34.2639, -110.0075.