U.S. Frost Dates by Weather Station

NOAA station USC00026796 · Arizona

Frost Dates for Prescott, AZ

NOAA weather station Prescott (USC00026796), Arizona · elevation 5205 ft (1587 m) · hardiness zone 7b*

  • Lower-risk planting dateafter May 15only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 2050% chance of a frost before it
  • Frost-free season172 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season at Prescott, AZSpring: a frost after April 14 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 7 in 1 year out of 10, before October 20 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 172 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 20Frost season at Prescott, AZSpring: a frost after April 14 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 7 in 1 year out of 10, before October 20 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 172 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 20
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 15October 7
50% (typical)April 30October 20
90% (likely)April 14November 4
Frost-free season (32°F, 50% chance)
172 days
Hard frost (28°F), last in spring, 50% chance after
April 13
Hard frost (28°F), first in fall, 50% chance before
October 31

The last 15 years (2006–2020 normals)

Typical last frost May 2 (2 days later than the 30-year normal), typical first fall frost October 17 (3 days earlier). Frost-free season 169 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 Prescott: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 15, 20% May 10, 30% May 6, 40% May 2, 50% April 30, 60% April 27, 70% April 23, 80% April 20, 90% April 14. Observed last spring frost in recent years: 2021 May 22, 2022 May 12, 2023 April 21, 2024 May 7, 2025 April 28, 2026 April 28.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 15Apr 30Apr 142021: May 222022: May 122023: April 212024: May 72025: April 282026: April 28Fall at Prescott: chance of a frost before this dateFall, chance of a frost before the date: 10% October 7, 20% October 11, 30% October 15, 40% October 17, 50% October 20, 60% October 23, 70% October 26, 80% October 30, 90% November 4. Observed first fall frost in recent years: 2021 October 13, 2022 October 24, 2023 October 13, 2025 November 25.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 7Oct 20Nov 42021: October 132022: October 242023: October 132025: November 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 22October 13
2022May 12October 24
2023April 21October 13
2024May 7incomplete record
2025April 28November 25
2026April 28season not over yet

What these dates mean

The cautious fall date in Prescott for finishing the harvest is October 7, when there is only a 10 % chance that a light frost has arrived earlier.

For light frost, the 50 % dates—April 30 in spring and October 20 in fall—are the points at which a frost is equally likely to occur before or after the date. The hard-frost 50 % dates are April 13 and October 31; a hard frost at 28 °F can damage or kill plants that survive a light frost at 32 °F.

Gardeners who wish to reduce risk for tender crops should plan to set them out after the cautious spring date of May 15, which carries only a 10 % chance of a later light frost, and to complete harvesting by the cautious fall date of October 7.

How to read the probabilities

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

  • Spring: "10% after May 15" 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 7" 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 Prescott, AZNumbered nearest stations: 1 — Jerome, AZ — 22 mi; 2 — Cordes, AZ — 24 mi; 3 — Walnut Creek, AZ — 33 mi; 4 — near Camp Verde, AZ — 34 mi; 5 — Bagdad, AZ — 42 mi.25 mi · 40 km1. Jerome, AZ — 22 mi12. Cordes, AZ — 24 mi23. Walnut Creek, AZ — 33 mi34. near Camp Verde, AZ — 34 mi45. Bagdad, AZ — 42 mi5
  1. Jerome, AZ 22 mi (36 km)
  2. Cordes, AZ 24 mi (38 km)
  3. Walnut Creek, AZ 33 mi (53 km)
  4. near Camp Verde, AZ 34 mi (55 km)
  5. Bagdad, AZ 42 mi (68 km)

Sources

* Hardiness zone 7b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 34.5706, -112.4322.