U.S. Frost Dates by Weather Station

NOAA station USC00459200 · Washington

Frost Dates for Whitman Mission, WA

NOAA weather station Whitman Mission (USC00459200), Washington · elevation 632 ft (193 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 18only 1 spring in 10 still has a frost later
  • Typical last frostMay 250% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season151 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Whitman Mission, WASpring: a frost after April 16 in 9 years out of 10, after May 2 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before October 1 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 151 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 2First frost ~Oct 1Frost season at Whitman Mission, WASpring: a frost after April 16 in 9 years out of 10, after May 2 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before October 1 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 151 days.JFMAMJJASONDLast frost ~May 2First frost ~Oct 1
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)May 18September 14
50% (typical)May 2October 1
90% (likely)April 16October 16
Frost-free season (32°F, 50% chance)
151 days
Hard frost (28°F), last in spring, 50% chance after
April 15
Hard frost (28°F), first in fall, 50% chance before
October 12

The last 15 years (2006–2020 normals)

Typical last frost May 2 (same as the 30-year normal), typical first fall frost October 2 (1 day later). Frost-free season 151 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 Whitman Mission: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 18, 20% May 13, 30% May 8, 40% May 5, 50% May 2, 60% April 30, 70% April 28, 80% April 24, 90% April 16. Observed last spring frost in recent years: 2021 April 22, 2022 May 11, 2023 April 24, 2024 May 3, 2026 April 28.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 18May 2Apr 162021: April 222022: May 112023: April 242024: May 32026: April 28Fall at Whitman Mission: chance of a frost before this dateFall, chance of a frost before the date: 10% September 14, 20% September 20, 30% September 25, 40% September 28, 50% October 1, 60% October 3, 70% October 5, 80% October 10, 90% October 16. Observed first fall frost in recent years: 2021 October 7, 2022 October 16, 2023 September 23, 2024 September 30.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 14Oct 1Oct 162021: October 72022: October 162023: September 232024: September 30
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 22October 7
2022May 11October 16
2023April 24September 23
2024May 3September 30
2025incomplete recordno data
2026April 28season not over yet

What these dates mean

Setting out tender crops on April 16 in Whitman Mission carries a 90 % chance of a light frost later that season, so gardeners face a gamble. The cautious spring date for tender crops is May 18, when only a 10 % chance of a later frost remains. In the fall, gardeners can finish harvesting tender crops by September 14, which has a 10 % chance that a frost has already arrived, while October 16 represents a gamble with a 90 % chance of an earlier frost.

The 50% dates represent the point of even odds for a light frost: the 50% date is May 2 in spring and the 50% date is October 1 in fall. The 50% hard-frost dates are April 15 and October 12; hard frost at 28 °F can injure plants that survive a light frost at 32 °F because the colder temperature is more destructive. These probabilities are drawn from 29 years of NOAA records for Whitman Mission.

How to read the probabilities

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

  • Spring: "10% after May 18" 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 14" 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 Whitman Mission, WANumbered nearest stations: 1 — Milton Freewater, OR — 7 mi; 2 — Walla Walla, WA — 9 mi; 3 — near Burbank, WA — 24 mi; 4 — Dayton, WA — 29 mi; 5 — Pendleton, OR — 31 mi.ORID25 mi · 40 km1. Milton Freewater, OR — 7 mi12. Walla Walla, WA — 9 mi23. near Burbank, WA — 24 mi34. Dayton, WA — 29 mi45. Pendleton, OR — 31 mi5
  1. Milton Freewater, OR 7 mi (12 km)
  2. Walla Walla, WA 9 mi (15 km)
  3. near Burbank, WA 24 mi (39 km)
  4. Dayton, WA 29 mi (47 km)
  5. Pendleton, OR 31 mi (50 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: 46.0436, -118.4628.