U.S. Frost Dates by Weather Station

NOAA station USC00458059 · Washington

Frost Dates for Stehekin, WA

NOAA weather station Stehekin 4 NW (USC00458059), Washington · elevation 1257 ft (383 m) · hardiness zone 7b*

  • Lower-risk planting dateafter May 12only 1 spring in 10 still has a frost later
  • Typical last frostApril 2750% chance of a frost after it
  • Typical first fall frostOctober 1750% chance of a frost before it
  • Frost-free season173 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season at Stehekin, WASpring: a frost after April 12 in 9 years out of 10, after April 27 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 17 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 173 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 27First frost ~Oct 17Frost season at Stehekin, WASpring: a frost after April 12 in 9 years out of 10, after April 27 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 17 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 173 days.JFMAMJJASONDLast frost ~Apr 27First frost ~Oct 17
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 12October 5
50% (typical)April 27October 17
90% (likely)April 12October 30
Frost-free season (32°F, 50% chance)
173 days
Hard frost (28°F), last in spring, 50% chance after
April 4
Hard frost (28°F), first in fall, 50% chance before
October 31

The last 15 years (2006–2020 normals)

Typical last frost April 26 (1 day earlier than the 30-year normal), typical first fall frost October 16 (1 day earlier). Frost-free season 173 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 Stehekin: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 12, 20% May 5, 30% May 2, 40% April 29, 50% April 27, 60% April 23, 70% April 20, 80% April 17, 90% April 12. Observed last spring frost in recent years: 2021 April 20, 2022 April 28, 2023 April 21, 2024 April 24, 2025 April 30, 2026 April 26.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 12Apr 27Apr 122021: April 202022: April 282023: April 212024: April 242025: April 302026: April 26Fall at Stehekin: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 8, 30% October 11, 40% October 14, 50% October 17, 60% October 20, 70% October 23, 80% October 26, 90% October 30. Observed first fall frost in recent years: 2021 October 8, 2023 October 25, 2025 October 14.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 17Oct 302021: October 82023: October 252025: October 14
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 20October 8
2022April 28incomplete record
2023April 21October 25
2024April 24incomplete record
2025April 30October 14
2026April 26season not over yet

What these dates mean

May 12 is the cautious spring date, offering only a 10% chance of a later light frost, so a gardener can plan to set out tender crops after that day.

The median light-frost dates are April 27 in spring and October 17 in fall; each marks a 50% chance of a frost occurring on either side of the date, providing a clear reference point for risk assessment. Hard-frost median dates are April 4 and October 31, and a hard frost at 28 °F can damage plants more severely than a light frost at 32 °F. These probabilities are drawn from 28 years of NOAA records.

October 5 is the cautious fall date, with only a 10% chance that a light frost has already arrived, allowing a gardener to schedule the final harvest of tender crops.

How to read the probabilities

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

  • Spring: "10% after May 12" 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 5" 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 Stehekin, WANumbered nearest stations: 1 — Mazama, WA — 22 mi; 2 — Winthrop, WA — 26 mi; 3 — Ross Dam, WA — 30 mi; 4 — Diablo Dam, WA — 32 mi; 5 — Newhalem, WA — 33 mi.WA25 mi · 40 km1. Mazama, WA — 22 mi12. Winthrop, WA — 26 mi23. Ross Dam, WA — 30 mi34. Diablo Dam, WA — 32 mi45. Newhalem, WA — 33 mi5
  1. Mazama, WA 22 mi (35 km)
  2. Winthrop, WA 26 mi (42 km)
  3. Ross Dam, WA 30 mi (49 km)
  4. Diablo Dam, WA 32 mi (51 km)
  5. Newhalem, WA 33 mi (52 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: 48.3508, -120.7264.