U.S. Frost Dates by Weather Station

NOAA station USC00456039 · Washington

Frost Dates for Odessa, WA

NOAA weather station Odessa (USC00456039), Washington · elevation 1543 ft (470 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 31only 1 spring in 10 still has a frost later
  • Typical last frostMay 1450% chance of a frost after it
  • Typical first fall frostSeptember 2650% chance of a frost before it
  • Frost-free season135 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Odessa, WASpring: a frost after April 29 in 9 years out of 10, after May 14 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 26 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 135 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 14First frost ~Sep 26Frost season at Odessa, WASpring: a frost after April 29 in 9 years out of 10, after May 14 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 26 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 135 days.JFMAMJJASONDLast frost ~May 14First frost ~Sep 26
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 31September 10
50% (typical)May 14September 26
90% (likely)April 29October 9
Frost-free season (32°F, 50% chance)
135 days
Hard frost (28°F), last in spring, 50% chance after
May 1
Hard frost (28°F), first in fall, 50% chance before
October 7

The last 15 years (2006–2020 normals)

Typical last frost May 11 (3 days earlier than the 30-year normal), typical first fall frost September 28 (2 days later). Frost-free season 138 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 Odessa: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 31, 20% May 26, 30% May 20, 40% May 16, 50% May 14, 60% May 11, 70% May 7, 80% May 3, 90% April 29. Observed last spring frost in recent years: 2021 May 8, 2022 May 10.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 31May 14Apr 292021: May 82022: May 10Fall at Odessa: chance of a frost before this dateFall, chance of a frost before the date: 10% September 10, 20% September 15, 30% September 19, 40% September 22, 50% September 26, 60% September 30, 70% October 2, 80% October 5, 90% October 9. Observed first fall frost in recent years: 2021 October 11, 2022 October 22.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 10Sep 26Oct 92021: October 112022: October 22
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
2021May 8October 11
2022May 10October 22
2023incomplete recordno data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

Setting out tender crops on April 29 in Odessa carries a 90% chance that a light frost will still occur later in the season, making that early planting a gamble. The 50% date for spring light frost is May 14, meaning there is an even chance of a frost later than this date, while the 50% date for fall light frost is September 26, meaning there is an even chance of a frost earlier than that date. For a cautious approach, gardeners should wait until the later spring date of May 31, which has only a 10% chance of a subsequent frost, and should aim to finish tender crops by September 10 in the fall, when only a 10% chance exists that a frost has arrived earlier. A hard frost at 28 °F, reflected by the 50% dates of May 1 in spring and October 7 in fall, can cause more severe damage than a light frost at 32 °F because it reaches temperatures that many plants cannot tolerate.

How to read the probabilities

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

  • Spring: "10% after May 31" 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 10" 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 Odessa, WANumbered nearest stations: 1 — Ritzville, WA — 21 mi; 2 — Wilbur, WA — 30 mi; 3 — Davenport, WA — 34 mi; 4 — Ephrata, WA — 38 mi; 5 — Coulee Dam, WA — 45 mi.WA25 mi · 40 km1. Ritzville, WA — 21 mi12. Wilbur, WA — 30 mi23. Davenport, WA — 34 mi34. Ephrata, WA — 38 mi45. Coulee Dam, WA — 45 mi5
  1. Ritzville, WA 21 mi (34 km)
  2. Wilbur, WA 30 mi (48 km)
  3. Davenport, WA 34 mi (54 km)
  4. Ephrata, WA 38 mi (62 km)
  5. Coulee Dam, WA 45 mi (73 km)

Sources

* Hardiness zone 6b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 47.3331, -118.6961.