U.S. Frost Dates by Weather Station

NOAA station USC00451939 · Washington

Frost Dates for Cushman Powerhouse #2, WA

NOAA weather station Cushman Powerhouse #2 (USC00451939), Washington · elevation 21 ft (6 m) · hardiness zone 9a*

  • Lower-risk planting dateafter April 17only 1 spring in 10 still has a frost later
  • Typical last frostMarch 2450% chance of a frost after it
  • Typical first fall frostNovember 1550% chance of a frost before it
  • Frost-free season235 daystypical year, 32°F
  • Hardiness zone9acalculated*

The year at a glance

Frost season at Cushman Powerhouse #2, WASpring: a frost after February 26 in 9 years out of 10, after March 24 in half of the years, after April 17 in 1 year out of 10. Fall: the first frost comes before October 25 in 1 year out of 10, before November 15 in half of the years, before December 8 in 9 years out of 10. Typical frost-free season: 235 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Mar 24First frost ~Nov 15Frost season at Cushman Powerhouse #2, WASpring: a frost after February 26 in 9 years out of 10, after March 24 in half of the years, after April 17 in 1 year out of 10. Fall: the first frost comes before October 25 in 1 year out of 10, before November 15 in half of the years, before December 8 in 9 years out of 10. Typical frost-free season: 235 days.JFMAMJJASONDLast frost ~Mar 24First frost ~Nov 15
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)April 17October 25
50% (typical)March 24November 15
90% (likely)February 26December 8
Frost-free season (32°F, 50% chance)
235 days
Hard frost (28°F), last in spring, 50% chance after
February 20
Hard frost (28°F), first in fall, 50% chance before
December 7

The last 15 years (2006–2020 normals)

Typical last frost March 27 (3 days later than the 30-year normal), typical first fall frost November 16 (1 day later). Frost-free season 234 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 Cushman Powerhouse #2: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 17, 20% April 9, 30% April 2, 40% March 29, 50% March 24, 60% March 19, 70% March 13, 80% March 5, 90% February 26. Observed last spring frost in recent years: 2021 April 13, 2022 April 17, 2023 April 6, 2024 March 13, 2025 March 18, 2026 April 17.Spring: last frostChance of a frost after this date10%50%90%Mar 1Apr 1May 1Apr 17Mar 24Feb 262021: April 132022: April 172023: April 62024: March 132025: March 182026: April 17Fall at Cushman Powerhouse #2: chance of a frost before this dateFall, chance of a frost before the date: 10% October 25, 20% November 1, 30% November 5, 40% November 10, 50% November 15, 60% November 20, 70% November 25, 80% December 1, 90% December 8. Observed first fall frost in recent years: 2021 November 22, 2022 November 9, 2023 October 28, 2024 November 19, 2025 November 30.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 25Nov 15Dec 82021: November 222022: November 92023: October 282024: November 192025: November 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 13November 22
2022April 17November 9
2023April 6October 28
2024March 13November 19
2025March 18November 30
2026April 17season not over yet

What these dates mean

April 17 is the cautious spring date at Cushman Powerhouse #2; with only a ten-percent chance of a light frost after that day, a gardener can plan to set out tender crops with minimal risk.

The 50% dates mark the median point of frost probability. The spring median is March 24, meaning there is an even chance of a light frost later than that day, while the fall median is November 15, indicating an even chance of a light frost earlier than that day. Across the 26-year record the interval between the two 32°F 50% dates measures 235 days, giving a sense of the typical frost-free window.

For fall, October 25 serves as the cautious date; with only a ten-percent chance that a light frost has arrived, it signals when tender crops should be finished. A hard frost at 28°F is more consequential than a light frost because the lower temperature can cause far more severe damage to plant tissue; the 50% hard-frost dates are February 20 in spring and December 7 in fall.

How to read the probabilities

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

  • Spring: "10% after April 17" 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 25" 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 Cushman Powerhouse #2, WANumbered nearest stations: 1 — Elma, WA — 27 mi; 2 — Olympia, WA — 30 mi; 3 — near Tacoma, WA — 36 mi; 4 — Seattle (Seattle-Tacoma Airport), WA — 40 mi; 5 — Humptulips Salmon Hatchery, WA — 40 mi.WA25 mi · 40 km1. Elma, WA — 27 mi12. Olympia, WA — 30 mi23. near Tacoma, WA — 36 mi34. Seattle (Seattle-Tacoma Airport), WA — 40 mi45. Humptulips Salmon Hatchery, WA — 40 mi5
  1. Elma, WA 27 mi (44 km)
  2. Olympia, WA 30 mi (48 km)
  3. near Tacoma, WA 36 mi (58 km)
  4. Seattle (Seattle-Tacoma Airport), WA 40 mi (64 km)
  5. Humptulips Salmon Hatchery, WA 40 mi (64 km)

Sources

* Hardiness zone 9a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 47.3706, -123.16.