U.S. Frost Dates by Weather Station

NOAA station USC00451760 · Washington

Frost Dates for Cougar, WA

NOAA weather station Cougar 6 E (USC00451760), Washington · elevation 659 ft (201 m) · hardiness zone 8b*

  • Lower-risk planting dateafter May 2only 1 spring in 10 still has a frost later
  • Typical last frostApril 150% chance of a frost after it
  • Typical first fall frostNovember 1850% chance of a frost before it
  • Frost-free season227 daystypical year, 32°F
  • Hardiness zone8bcalculated*

The year at a glance

Frost season at Cougar, WASpring: a frost after March 6 in 9 years out of 10, after April 1 in half of the years, after May 2 in 1 year out of 10. Fall: the first frost comes before October 29 in 1 year out of 10, before November 18 in half of the years, before December 8 in 9 years out of 10. Typical frost-free season: 227 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 1First frost ~Nov 18Frost season at Cougar, WASpring: a frost after March 6 in 9 years out of 10, after April 1 in half of the years, after May 2 in 1 year out of 10. Fall: the first frost comes before October 29 in 1 year out of 10, before November 18 in half of the years, before December 8 in 9 years out of 10. Typical frost-free season: 227 days.JFMAMJJASONDLast frost ~Apr 1First frost ~Nov 18
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 2October 29
50% (typical)April 1November 18
90% (likely)March 6December 8
Frost-free season (32°F, 50% chance)
227 days
Hard frost (28°F), last in spring, 50% chance after
February 22
Hard frost (28°F), first in fall, 50% chance before
December 7

The last 15 years (2006–2020 normals)

Typical last frost March 29 (3 days earlier than the 30-year normal), typical first fall frost November 21 (3 days later). Frost-free season 233 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 Cougar: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 2, 20% April 23, 30% April 15, 40% April 6, 50% April 1, 60% March 29, 70% March 24, 80% March 16, 90% March 6. Observed last spring frost in recent years: 2021 April 11, 2022 April 13, 2023 April 13, 2026 April 17.Spring: last frostChance of a frost after this date10%50%90%Mar 1Apr 1May 1May 2Apr 1Mar 62021: April 112022: April 132023: April 132026: April 17Fall at Cougar: chance of a frost before this dateFall, chance of a frost before the date: 10% October 29, 20% November 5, 30% November 10, 40% November 14, 50% November 18, 60% November 23, 70% November 27, 80% December 2, 90% December 8. Observed first fall frost in recent years: 2021 December 10, 2022 November 9, 2023 October 28.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 29Nov 18Dec 82021: December 102022: November 92023: October 28
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 11December 10
2022April 13November 9
2023April 13October 28
2024incomplete recordincomplete record
2025incomplete recordincomplete record
2026April 17season not over yet

What these dates mean

May 2 is the cautious spring date for setting out tender crops in Cougar; with only a 10 % chance of a light frost later than that day, a gardener can plan to transplant seedlings with relatively low risk. The corresponding cautious fall date is October 29, when there is just a 10 % chance that a light frost has arrived earlier, allowing the final harvest of tender vegetables before frost becomes likely.

The 50% date is April 1, meaning there is a 50 % chance of a light frost later than this date, and the 50% fall date is November 18, with a 50 % chance of a light frost earlier than this date. The 50% hard-frost dates are February 22 in spring and December 7 in fall; each marks the point at which a hard frost is equally likely to have occurred or not. A hard frost at 28 °F can damage plant tissue that 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 May 2" 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 29" 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 Cougar, WANumbered nearest stations: 1 — near Carson, WA — 17 mi; 2 — Battle Ground, WA — 25 mi; 3 — near Cascade Locks, OR — 32 mi; 4 — Vancouver, WA — 34 mi; 5 — Longview, WA — 35 mi.25 mi · 40 km1. near Carson, WA — 17 mi12. Battle Ground, WA — 25 mi23. near Cascade Locks, OR — 32 mi34. Vancouver, WA — 34 mi45. Longview, WA — 35 mi5
  1. near Carson, WA 17 mi (28 km)
  2. Battle Ground, WA 25 mi (41 km)
  3. near Cascade Locks, OR 32 mi (51 km)
  4. Vancouver, WA 34 mi (55 km)
  5. Longview, WA 35 mi (56 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: 46.0625, -122.2044.