U.S. Frost Dates by Weather Station

NOAA station USC00351897 · Oregon

Frost Dates for Cottage Grove, OR

NOAA weather station Cottage Grove 2 E (USC00351897), Oregon · elevation 595 ft (181 m) · hardiness zone 8b*

  • Lower-risk planting dateafter May 10only 1 spring in 10 still has a frost later
  • Typical last frostApril 2450% chance of a frost after it
  • Typical first fall frostOctober 2550% chance of a frost before it
  • Frost-free season183 daystypical year, 32°F
  • Hardiness zone8bcalculated*

The year at a glance

Frost season at Cottage Grove, ORSpring: a frost after March 31 in 9 years out of 10, after April 24 in half of the years, after May 10 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 25 in half of the years, before November 16 in 9 years out of 10. Typical frost-free season: 183 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 24First frost ~Oct 25Frost season at Cottage Grove, ORSpring: a frost after March 31 in 9 years out of 10, after April 24 in half of the years, after May 10 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 25 in half of the years, before November 16 in 9 years out of 10. Typical frost-free season: 183 days.JFMAMJJASONDLast frost ~Apr 24First frost ~Oct 25
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 10September 30
50% (typical)April 24October 25
90% (likely)March 31November 16
Frost-free season (32°F, 50% chance)
183 days
Hard frost (28°F), last in spring, 50% chance after
March 23
Hard frost (28°F), first in fall, 50% chance before
November 18

The last 15 years (2006–2020 normals)

Typical last frost April 24 (same as the 30-year normal), typical first fall frost October 28 (3 days later). Frost-free season 189 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 Cottage Grove: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 10, 20% May 4, 30% May 1, 40% April 28, 50% April 24, 60% April 20, 70% April 15, 80% April 9, 90% March 31. Observed last spring frost in recent years: 2021 April 16, 2022 May 12, 2023 April 14, 2024 May 26, 2025 April 25.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Jun 1May 10Apr 24Mar 312021: April 162022: May 122023: April 142024: May 262025: April 25Fall at Cottage Grove: chance of a frost before this dateFall, chance of a frost before the date: 10% September 30, 20% October 9, 30% October 15, 40% October 20, 50% October 25, 60% October 29, 70% November 1, 80% November 7, 90% November 16. Observed first fall frost in recent years: 2021 October 13, 2022 November 4, 2023 October 29, 2024 October 25.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 30Oct 25Nov 162021: October 132022: November 42023: October 292024: October 25
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 16October 13
2022May 12November 4
2023April 14October 29
2024May 26October 25
2025April 25incomplete record
2026incomplete recordseason not over yet

What these dates mean

The 183 days between the 50% light-frost dates of April 24 and October 25 in Cottage Grove frame the window during which tender crops can be grown. The April 24 date marks the point where a light frost is equally likely to occur later, while the October 25 date marks the point where a light frost is equally likely to have occurred earlier; each represents a median odds moment for gardeners.

In a cautious plan, the spring LATE date of May 10, with only a 10% chance of a frost later, is the recommended day to set out tender crops. In the fall, the EARLY date of September 30, with only a 10% chance that a frost has arrived earlier, is the prudent day to finish harvesting tender crops. A hard frost at 28 °F can injure plants that would survive a 32 °F light frost, so the 28 °F thresholds of March 23 and November 18 are especially important for protecting 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 10" 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 30" 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 Cottage Grove, ORNumbered nearest stations: 1 — Dorena, OR — 3 mi; 2 — near Lowell, OR — 16 mi; 3 — Drain, OR — 17 mi; 4 — near Eugene, OR — 25 mi; 5 — Leaburg, OR — 27 mi.25 mi · 40 km1. Dorena, OR — 3 mi12. near Lowell, OR — 16 mi23. Drain, OR — 17 mi34. near Eugene, OR — 25 mi45. Leaburg, OR — 27 mi5
  1. Dorena, OR 3 mi (5 km)
  2. near Lowell, OR 16 mi (25 km)
  3. Drain, OR 17 mi (28 km)
  4. near Eugene, OR 25 mi (40 km)
  5. Leaburg, OR 27 mi (44 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: 43.7917, -123.0275.