U.S. Frost Dates by Weather Station

NOAA station USC00029542 · Arizona

Frost Dates for Wupatki National Monument, AZ

NOAA weather station Wupatki National Monument (USC00029542), Arizona · elevation 4908 ft (1496 m) · hardiness zone 8a*

  • Lower-risk planting dateafter April 30only 1 spring in 10 still has a frost later
  • Typical last frostApril 750% chance of a frost after it
  • Typical first fall frostNovember 350% chance of a frost before it
  • Frost-free season206 daystypical year, 32°F
  • Hardiness zone8acalculated*

The year at a glance

Frost season at Wupatki National Monument, AZSpring: a frost after March 17 in 9 years out of 10, after April 7 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 19 in 1 year out of 10, before November 3 in half of the years, before November 17 in 9 years out of 10. Typical frost-free season: 206 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 7First frost ~Nov 3Frost season at Wupatki National Monument, AZSpring: a frost after March 17 in 9 years out of 10, after April 7 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 19 in 1 year out of 10, before November 3 in half of the years, before November 17 in 9 years out of 10. Typical frost-free season: 206 days.JFMAMJJASONDLast frost ~Apr 7First frost ~Nov 3
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.Today

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)April 30October 19
50% (typical)April 7November 3
90% (likely)March 17November 17
Frost-free season (32°F, 50% chance)
206 days
Hard frost (28°F), last in spring, 50% chance after
March 17
Hard frost (28°F), first in fall, 50% chance before
November 14

The last 15 years (2006–2020 normals)

Typical last frost April 9 (2 days later than the 30-year normal), typical first fall frost October 31 (3 days earlier). Frost-free season 204 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 Wupatki National Monument: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 30, 20% April 22, 30% April 17, 40% April 12, 50% April 7, 60% April 3, 70% March 31, 80% March 25, 90% March 17. Observed last spring frost in recent years: 2021 March 27, 2022 April 13, 2023 April 6, 2024 April 6, 2025 April 4, 2026 April 18.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 30Apr 7Mar 172021: March 272022: April 132023: April 62024: April 62025: April 42026: April 18Fall at Wupatki National Monument: chance of a frost before this dateFall, chance of a frost before the date: 10% October 19, 20% October 24, 30% October 27, 40% October 30, 50% November 3, 60% November 5, 70% November 8, 80% November 12, 90% November 17. Observed first fall frost in recent years: 2021 November 22, 2022 October 25, 2023 October 30, 2024 October 31.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 19Nov 3Nov 172021: November 222022: October 252023: October 302024: October 31
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
2021March 27November 22
2022April 13October 25
2023April 6October 30
2024April 6October 31
2025April 4incomplete record
2026April 18season not over yet

What these dates mean

Setting out tender crops on March 17 in spring carries a 90% chance of a light frost, a clear gamble for growers at Wupatki National Monument. The cautious alternative is April 30, when only a 10% chance of a later frost remains, making it the safer marker for planting tender varieties.

The 50% light-frost dates are April 7 for spring and November 3 for fall; at each of these points there is an even chance of a frost occurring later (spring) or earlier (fall). For the fall season the cautious date to finish harvesting tender crops is October 19, with just a 10% chance that frost has already arrived. Hard-frost dates—March 17 in spring and November 14 in fall—mark the median moment a 28 °F frost may appear, and a hard frost can damage plants more severely than a light 32 °F frost.

How to read the probabilities

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

  • Spring: "10% after April 30" 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 19" 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 Wupatki National Monument, AZNumbered nearest stations: 1 — near Flagstaff, AZ — 31 mi; 2 — Winslow, AZ — 50 mi; 3 — near Grand Canyon Village, AZ — 57 mi; 4 — Jerome, AZ — 68 mi; 5 — near Camp Verde, AZ — 68 mi.AZ50 mi · 80 km1. near Flagstaff, AZ — 31 mi12. Winslow, AZ — 50 mi23. near Grand Canyon Village, AZ — 57 mi34. Jerome, AZ — 68 mi45. near Camp Verde, AZ — 68 mi5
  1. near Flagstaff, AZ 31 mi (50 km)
  2. Winslow, AZ 50 mi (81 km)
  3. near Grand Canyon Village, AZ 57 mi (92 km)
  4. Jerome, AZ 68 mi (109 km)
  5. near Camp Verde, AZ 68 mi (110 km)

Sources

* Hardiness zone 8a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 35.5247, -111.3703.