U.S. Frost Dates by Weather Station

NOAA station USW00024160 · Washington

Frost Dates for Walla Walla, WA

NOAA weather station Walla Walla Regional Airport (USW00024160), Washington · elevation 1166 ft (355 m) · hardiness zone 7b*

  • Lower-risk planting dateafter April 22only 1 spring in 10 still has a frost later
  • Typical last frostMarch 2750% chance of a frost after it
  • Typical first fall frostOctober 3150% chance of a frost before it
  • Frost-free season219 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season at Walla Walla, WASpring: a frost after March 3 in 9 years out of 10, after March 27 in half of the years, after April 22 in 1 year out of 10. Fall: the first frost comes before October 15 in 1 year out of 10, before October 31 in half of the years, before November 17 in 9 years out of 10. Typical frost-free season: 219 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Mar 27First frost ~Oct 31Frost season at Walla Walla, WASpring: a frost after March 3 in 9 years out of 10, after March 27 in half of the years, after April 22 in 1 year out of 10. Fall: the first frost comes before October 15 in 1 year out of 10, before October 31 in half of the years, before November 17 in 9 years out of 10. Typical frost-free season: 219 days.JFMAMJJASONDLast frost ~Mar 27First frost ~Oct 31
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 22October 15
50% (typical)March 27October 31
90% (likely)March 3November 17
Frost-free season (32°F, 50% chance)
219 days
Hard frost (28°F), last in spring, 50% chance after
March 4
Hard frost (28°F), first in fall, 50% chance before
November 14

The last 15 years (2006–2020 normals)

Typical last frost March 31 (4 days later than the 30-year normal), typical first fall frost November 2 (2 days later). Frost-free season 213 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 Walla Walla: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 22, 20% April 13, 30% April 5, 40% March 31, 50% March 27, 60% March 22, 70% March 16, 80% March 10, 90% March 3. Observed last spring frost in recent years: 2021 April 13, 2022 April 16, 2023 April 5, 2024 March 14, 2025 April 17, 2026 March 27.Spring: last frostChance of a frost after this date10%50%90%Mar 1Apr 1May 1Apr 22Mar 27Mar 32021: April 132022: April 162023: April 52024: March 142025: April 172026: March 27Fall at Walla Walla: chance of a frost before this dateFall, chance of a frost before the date: 10% October 15, 20% October 20, 30% October 24, 40% October 28, 50% October 31, 60% November 3, 70% November 6, 80% November 11, 90% November 17. Observed first fall frost in recent years: 2021 October 12, 2022 November 8, 2023 October 27, 2024 November 6, 2025 November 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 15Oct 31Nov 172021: October 122022: November 82023: October 272024: November 62025: November 19
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
2021April 13October 12
2022April 16November 8
2023April 5October 27
2024March 14November 6
2025April 17November 19
2026March 27season not over yet

What these dates mean

Setting out tender crops on March 3 carries a 90 % chance of a light frost and is therefore a gamble for Walla Walla gardeners.

The 50 % date for light frost in spring is March 27; there is a 50 % chance of a frost later than this date. In fall the 50 % date is October 31, meaning a 50 % chance of a frost earlier than this date. The 50 % dates for hard frost are March 4 in spring and November 14 in fall.

A cautious planting schedule therefore uses the April 22 light-frost date to start tender crops, and the October 15 light-frost date to finish harvesting them. A hard frost at 28 °F can damage or kill plants that survive a 32 °F light frost, making it a more serious threat.

How to read the probabilities

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

  • Spring: "10% after April 22" 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 15" 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 Walla Walla, WANumbered nearest stations: 1 — Whitman Mission, WA — 9 mi; 2 — Milton Freewater, OR — 12 mi; 3 — Dayton, WA — 20 mi; 4 — near Burbank, WA — 30 mi; 5 — Pendleton, OR — 39 mi.ORID25 mi · 40 km1. Whitman Mission, WA — 9 mi12. Milton Freewater, OR — 12 mi23. Dayton, WA — 20 mi34. near Burbank, WA — 30 mi45. Pendleton, OR — 39 mi5
  1. Whitman Mission, WA 9 mi (15 km)
  2. Milton Freewater, OR 12 mi (19 km)
  3. Dayton, WA 20 mi (33 km)
  4. near Burbank, WA 30 mi (49 km)
  5. Pendleton, OR 39 mi (63 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: 46.0947, -118.2869.