U.S. Frost Dates by Weather Station

NOAA station USC00029158 · Arizona

Frost Dates for Walnut Creek, AZ

NOAA weather station Walnut Creek (USC00029158), Arizona · elevation 5090 ft (1551 m) · hardiness zone 7a*

  • Lower-risk planting dateafter June 11only 1 spring in 10 still has a frost later
  • Typical last frostMay 2450% chance of a frost after it
  • Typical first fall frostOctober 750% chance of a frost before it
  • Frost-free season135 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Walnut Creek, AZSpring: a frost after May 7 in 9 years out of 10, after May 24 in half of the years, after June 11 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 7 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 135 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 24First frost ~Oct 7Frost season at Walnut Creek, AZSpring: a frost after May 7 in 9 years out of 10, after May 24 in half of the years, after June 11 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 7 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 135 days.JFMAMJJASONDLast frost ~May 24First frost ~Oct 7
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)June 11September 27
50% (typical)May 24October 7
90% (likely)May 7October 23
Frost-free season (32°F, 50% chance)
135 days
Hard frost (28°F), last in spring, 50% chance after
May 6
Hard frost (28°F), first in fall, 50% chance before
October 18

The last 15 years (2006–2020 normals)

Typical last frost May 26 (2 days later than the 30-year normal), typical first fall frost October 6 (1 day earlier). Frost-free season 131 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 Walnut Creek: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 11, 20% June 5, 30% June 1, 40% May 29, 50% May 24, 60% May 20, 70% May 17, 80% May 13, 90% May 7. Observed last spring frost in recent years: 2021 May 24, 2022 May 14, 2023 June 24, 2024 May 7, 2025 May 16, 2026 May 21.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jul 1Jun 11May 24May 72021: May 242022: May 142023: June 242024: May 72025: May 162026: May 21Fall at Walnut Creek: chance of a frost before this dateFall, chance of a frost before the date: 10% September 27, 20% October 1, 30% October 2, 40% October 5, 50% October 7, 60% October 10, 70% October 13, 80% October 17, 90% October 23. Observed first fall frost in recent years: 2021 October 11, 2022 October 24, 2023 October 14, 2024 September 18, 2025 October 16.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 27Oct 7Oct 232021: October 112022: October 242023: October 142024: September 182025: 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
2021May 24October 11
2022May 14October 24
2023June 24October 14
2024May 7September 18
2025May 16October 16
2026May 21season not over yet

What these dates mean

Setting out tender crops on the early spring date, May 7, carries a 90% chance of a frost later than that date, making it a gamble for Walnut Creek gardeners. The cautious date for planting tender crops in spring is June 11, when only a 10% chance of a later frost remains.

The 50% date is May 24, meaning there is an even chance of a frost occurring after that point, and the 50% date is October 7, meaning an even chance of a frost occurring before that point. In fall the cautious date to finish harvesting tender crops is September 27, with just a 10% chance of a frost earlier than that date; October 23 is a gamble, carrying a 90% chance of an earlier frost. The median hard-frost dates are May 6 and October 18; a hard frost at 28 °F can damage plants more severely than a light frost at 32 °F.

How to read the probabilities

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

  • Spring: "10% after June 11" 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 27" 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 Walnut Creek, AZNumbered nearest stations: 1 — Seligman, AZ — 28 mi; 2 — Bagdad, AZ — 31 mi; 3 — Prescott, AZ — 33 mi; 4 — Jerome, AZ — 41 mi; 5 — Cordes, AZ — 57 mi.25 mi · 40 km1. Seligman, AZ — 28 mi12. Bagdad, AZ — 31 mi23. Prescott, AZ — 33 mi34. Jerome, AZ — 41 mi45. Cordes, AZ — 57 mi5
  1. Seligman, AZ 28 mi (45 km)
  2. Bagdad, AZ 31 mi (50 km)
  3. Prescott, AZ 33 mi (53 km)
  4. Jerome, AZ 41 mi (67 km)
  5. Cordes, AZ 57 mi (91 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: 34.9281, -112.8097.