U.S. Frost Dates by Weather Station

NOAA station USC00354622 · Oregon

Frost Dates for La Grande, OR

NOAA weather station La Grande (USC00354622), Oregon · elevation 2755 ft (840 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 26only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season146 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at La Grande, ORSpring: a frost after April 21 in 9 years out of 10, after May 6 in half of the years, after May 26 in 1 year out of 10. Fall: the first frost comes before September 17 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: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 1Frost season at La Grande, ORSpring: a frost after April 21 in 9 years out of 10, after May 6 in half of the years, after May 26 in 1 year out of 10. Fall: the first frost comes before September 17 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: 146 days.JFMAMJJASONDLast frost ~May 6First 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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 26September 17
50% (typical)May 6October 1
90% (likely)April 21October 16
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 19
Hard frost (28°F), first in fall, 50% chance before
October 14

The last 15 years (2006–2020 normals)

Typical last frost May 9 (3 days later than the 30-year normal), typical first fall frost October 2 (1 day later). Frost-free season 148 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 La Grande: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 26, 20% May 17, 30% May 13, 40% May 9, 50% May 6, 60% May 3, 70% April 30, 80% April 27, 90% April 21. Observed last spring frost in recent years: 2021 April 21, 2023 May 1, 2024 May 4, 2025 May 19, 2026 April 28.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 26May 6Apr 212021: April 212023: May 12024: May 42025: May 192026: April 28Fall at La Grande: chance of a frost before this dateFall, chance of a frost before the date: 10% September 17, 20% September 22, 30% September 27, 40% September 30, 50% October 1, 60% October 4, 70% October 7, 80% October 11, 90% October 16. Observed first fall frost in recent years: 2021 October 7, 2022 October 18, 2024 October 3, 2025 October 9.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 17Oct 1Oct 162021: October 72022: October 182024: October 32025: October 9
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 21October 7
2022incomplete recordOctober 18
2023May 1incomplete record
2024May 4October 3
2025May 19October 9
2026April 28season not over yet

What these dates mean

The 146 days between the 50% dates in La Grande, May 6 and October 1, define the period in which a light frost is equally likely to have occurred or not. For a gardener this interval marks the span of moderate risk for tender crops, with the median dates themselves serving only as reference points.

The cautious spring date for setting out tender crops is May 26, when there is only a 10 % chance of a light frost later; planting on April 21 would be a gamble with a 90 % chance of frost. In fall, the cautious date to finish harvesting tender crops is September 17, where only a 10 % chance of a light frost has arrived earlier; extending to October 16 would be a gamble with a 90 % chance of frost.

The median hard-frost dates are April 19 and October 14, and a hard frost at 28 °F can damage or kill plants that survive 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 26" 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 17" 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 La Grande, ORNumbered nearest stations: 1 — Baker City, OR — 35 mi; 2 — Pilot Rock, OR — 38 mi; 3 — Pendleton, OR — 46 mi; 4 — Milton Freewater, OR — 46 mi; 5 — Whitman Mission, WA — 54 mi.ORID25 mi · 40 km1. Baker City, OR — 35 mi12. Pilot Rock, OR — 38 mi23. Pendleton, OR — 46 mi34. Milton Freewater, OR — 46 mi45. Whitman Mission, WA — 54 mi5
  1. Baker City, OR 35 mi (57 km)
  2. Pilot Rock, OR 38 mi (61 km)
  3. Pendleton, OR 46 mi (74 km)
  4. Milton Freewater, OR 46 mi (74 km)
  5. Whitman Mission, WA 54 mi (86 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: 45.3167, -118.0747.