U.S. Frost Dates by Weather Station

NOAA station USC00353047 · Oregon

Frost Dates near Sweet Home, OR

NOAA weather station Foster Dam (USC00353047), Oregon · elevation 550 ft (168 m) · hardiness zone 8b*

Sweet Home is the nearest town to the station (3.4 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 5only 1 spring in 10 still has a frost later
  • Typical last frostApril 1250% chance of a frost after it
  • Typical first fall frostOctober 2850% chance of a frost before it
  • Frost-free season197 daystypical year, 32°F
  • Hardiness zone8bcalculated*

The year at a glance

Frost season near Sweet Home, ORSpring: a frost after March 16 in 9 years out of 10, after April 12 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 28 in half of the years, before November 21 in 9 years out of 10. Typical frost-free season: 197 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 12First frost ~Oct 28Frost season near Sweet Home, ORSpring: a frost after March 16 in 9 years out of 10, after April 12 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 28 in half of the years, before November 21 in 9 years out of 10. Typical frost-free season: 197 days.JFMAMJJASONDLast frost ~Apr 12First frost ~Oct 28
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 5October 5
50% (typical)April 12October 28
90% (likely)March 16November 21
Frost-free season (32°F, 50% chance)
197 days
Hard frost (28°F), last in spring, 50% chance after
March 9
Hard frost (28°F), first in fall, 50% chance before
November 18

The last 15 years (2006–2020 normals)

Typical last frost April 21 (9 days later than the 30-year normal), typical first fall frost October 27 (1 day earlier). Frost-free season 186 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 near Sweet Home: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 5, 20% April 30, 30% April 24, 40% April 18, 50% April 12, 60% April 6, 70% April 1, 80% March 26, 90% March 16. Observed last spring frost in recent years: 2021 April 15, 2022 April 16, 2023 April 21, 2024 April 23, 2025 April 25, 2026 March 28.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 5Apr 12Mar 162021: April 152022: April 162023: April 212024: April 232025: April 252026: March 28Fall near Sweet Home: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 14, 30% October 20, 40% October 24, 50% October 28, 60% November 1, 70% November 6, 80% November 13, 90% November 21. Observed first fall frost in recent years: 2021 November 17, 2022 November 9, 2023 October 28, 2024 October 26.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 5Oct 28Nov 212021: November 172022: November 92023: October 282024: October 26
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 15November 17
2022April 16November 9
2023April 21October 28
2024April 23October 26
2025April 25incomplete record
2026March 28season not over yet

What these dates mean

Setting out tender crops on March 16 in the Sweet Home area carries a 90% chance of a light frost later that season, so it is a gamble for growers. The cautious spring date is May 5, when only a 10% chance of a light frost later remains, and the cautious fall date is October 5, with a 10% chance of a light frost earlier. For a gardener, the 50% light-frost date of April 12 marks the point of even odds for a frost, while the 50% hard-frost date of March 9 indicates a fifty-fifty chance of temperatures reaching 28 °F. In the autumn the 50% light-frost date is October 28 and the 50% hard-frost date is November 18, each representing equal likelihood of frost at those thresholds.

The lower 28 °F of a hard frost can damage plant tissue that would survive the 32 °F of a light frost, making it a more critical threshold.

How to read the probabilities

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

  • Spring: "10% after May 5" 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 Sweet Home, ORNumbered nearest stations: 1 — Lacomb, OR — 15 mi; 2 — Leaburg, OR — 22 mi; 3 — Stayton, OR — 27 mi; 4 — near Corvallis, OR — 30 mi; 5 — near Eugene, OR — 34 mi.25 mi · 40 km1. Lacomb, OR — 15 mi12. Leaburg, OR — 22 mi23. Stayton, OR — 27 mi34. near Corvallis, OR — 30 mi45. near Eugene, OR — 34 mi5
  1. Lacomb, OR 15 mi (24 km)
  2. Leaburg, OR 22 mi (35 km)
  3. Stayton, OR 27 mi (43 km)
  4. near Corvallis, OR 30 mi (48 km)
  5. near Eugene, OR 34 mi (54 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: 44.4139, -122.6728.