U.S. Frost Dates by Weather Station

NOAA station USC00028865 · Arizona

Frost Dates near Tubac, AZ

NOAA weather station Tumacacori National Monument (USC00028865), Arizona · elevation 3267 ft (996 m) · hardiness zone 8b*

Tubac is the nearest town to the station (3.1 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter April 25only 1 spring in 10 still has a frost later
  • Typical last frostApril 550% chance of a frost after it
  • Typical first fall frostNovember 1050% chance of a frost before it
  • Frost-free season217 daystypical year, 32°F
  • Hardiness zone8bcalculated*

The year at a glance

Frost season near Tubac, AZSpring: a frost after March 13 in 9 years out of 10, after April 5 in half of the years, after April 25 in 1 year out of 10. Fall: the first frost comes before October 21 in 1 year out of 10, before November 10 in half of the years, before November 27 in 9 years out of 10. Typical frost-free season: 217 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 5First frost ~Nov 10Frost season near Tubac, AZSpring: a frost after March 13 in 9 years out of 10, after April 5 in half of the years, after April 25 in 1 year out of 10. Fall: the first frost comes before October 21 in 1 year out of 10, before November 10 in half of the years, before November 27 in 9 years out of 10. Typical frost-free season: 217 days.JFMAMJJASONDLast frost ~Apr 5First frost ~Nov 10
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)April 25October 21
50% (typical)April 5November 10
90% (likely)March 13November 27
Frost-free season (32°F, 50% chance)
217 days
Hard frost (28°F), last in spring, 50% chance after
March 12
Hard frost (28°F), first in fall, 50% chance before
November 20

The last 15 years (2006–2020 normals)

Typical last frost April 9 (4 days later than the 30-year normal), typical first fall frost November 9 (1 day earlier). Frost-free season 212 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 near Tubac: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 25, 20% April 19, 30% April 13, 40% April 9, 50% April 5, 60% April 1, 70% March 28, 80% March 22, 90% March 13. Observed last spring frost in recent years: 2021 March 28, 2024 April 7, 2025 April 5, 2026 March 8.Spring: last frostChance of a frost after this date10%50%90%Mar 1Apr 1May 1Apr 25Apr 5Mar 132021: March 282024: April 72025: April 52026: March 8Fall near Tubac: chance of a frost before this dateFall, chance of a frost before the date: 10% October 21, 20% October 30, 30% November 3, 40% November 7, 50% November 10, 60% November 14, 70% November 17, 80% November 21, 90% November 27. Observed first fall frost in recent years: 2021 October 13, 2022 October 25, 2023 November 10, 2024 November 5.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 21Nov 10Nov 272021: October 132022: October 252023: November 102024: November 5
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 28October 13
2022incomplete recordOctober 25
2023incomplete recordNovember 10
2024April 7November 5
2025April 5incomplete record
2026March 8season not over yet

What these dates mean

Setting out tender crops on the early spring date of March 13 in the Tubac area carries a 90 % chance of a frost later, making it a gamble. The cautious spring date for tender crops is April 25, when the chance of a frost later is only 10 %.

The 50% date in spring is April 5, meaning a 50 % chance of a frost later than this date, and the 50% date in fall is November 10, meaning a 50 % chance of a frost earlier than this date. The cautious fall date to finish harvesting tender crops is October 21, with a 10 % chance of a frost earlier. The hard-frost 50% dates are March 12 and November 20.

A hard frost at 28 °F can damage plant tissue that typically survives 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 April 25" 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 21" 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 Tubac, AZNumbered nearest stations: 1 — Sasabe, AZ — 30 mi; 2 — near Sierra Vista Southeast, AZ — 49 mi; 3 — Benson, AZ — 52 mi; 4 — Tombstone, AZ — 59 mi; 5 — near Douglas, AZ — 85 mi.AZ25 mi · 40 km1. Sasabe, AZ — 30 mi12. near Sierra Vista Southeast, AZ — 49 mi23. Benson, AZ — 52 mi34. Tombstone, AZ — 59 mi45. near Douglas, AZ — 85 mi5
  1. Sasabe, AZ 30 mi (48 km)
  2. near Sierra Vista Southeast, AZ 49 mi (79 km)
  3. Benson, AZ 52 mi (84 km)
  4. Tombstone, AZ 59 mi (94 km)
  5. near Douglas, AZ 85 mi (137 km)

Sources

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

Station coordinates: 31.5678, -111.0497.