Last spring frost
Apr 12
Frost Dates for Cottage Grove, OR
First fall frost
Nov 1
Growing season
205 days
Hardiness zone
8b
In an average year around Cottage Grove, OR, the last spring frost (32°F) is about Apr 12 and the first fall frost is about Nov 1, giving roughly a 205-day growing season. To be safe most years, wait until Mar 18 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | May 20 | May 4 | Apr 19 |
| Freeze (32°F) | May 4 | Apr 12 | Mar 18 |
| Hard (28°F) | Apr 6 | Mar 10 | Feb 4 |
| Severe (24°F) | Mar 7 | Feb 2 | Dec 20 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 20 | May 15 | May 11 | May 8 | May 4 | May 2 | Apr 29 | Apr 25 | Apr 19 |
| 32°F | May 4 | Apr 29 | Apr 22 | Apr 16 | Apr 12 | Apr 8 | Apr 2 | Mar 29 | Mar 18 |
| 28°F | Apr 6 | Mar 29 | Mar 22 | Mar 16 | Mar 10 | Mar 3 | Feb 26 | Feb 19 | Feb 4 |
| 24°F | Mar 7 | Feb 27 | Feb 20 | Feb 11 | Feb 2 | Jan 22 | Jan 11 | Jan 1 | Dec 20 |
| 20°F | Feb 21 | Feb 9 | Jan 27 | Jan 13 | Jan 5 | Dec 31 | Dec 26 | Dec 18 | Dec 7 |
| 16°F | Feb 5 | Jan 14 | Jan 3 | Dec 30 | Dec 27 | Dec 23 | Dec 16 | Dec 12 | Dec 5 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Oct 1 | Oct 18 | Nov 4 |
| Freeze (32°F) | Oct 16 | Nov 1 | Nov 23 |
| Hard (28°F) | Oct 28 | Nov 21 | Dec 20 |
| Severe (24°F) | Nov 9 | Dec 16 | Jan 31 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 5 | Oct 11 | Oct 14 | Oct 18 | Oct 21 | Oct 24 | Oct 29 | Nov 4 |
| 32°F | Oct 16 | Oct 22 | Oct 26 | Oct 30 | Nov 1 | Nov 6 | Nov 10 | Nov 15 | Nov 23 |
| 28°F | Oct 28 | Nov 4 | Nov 10 | Nov 15 | Nov 21 | Nov 28 | Dec 2 | Dec 9 | Dec 20 |
| 24°F | Nov 9 | Nov 23 | Dec 1 | Dec 8 | Dec 16 | Dec 22 | Dec 30 | Jan 9 | Jan 31 |
| 20°F | Dec 1 | Dec 8 | Dec 16 | Dec 22 | Dec 27 | Dec 31 | Jan 7 | Jan 21 | Feb 11 |
| 16°F | Dec 5 | Dec 10 | Dec 14 | Dec 20 | Dec 24 | Dec 28 | Jan 1 | Jan 13 | Feb 3 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Cottage Grove Dam, Or, about 2 miles away@if(!empty($station['elevation_ft'])), at 831 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Cottage Grove, OR?
On average, the last spring frost (32°F) around Cottage Grove, OR is about Apr 12. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 18.
When is the first frost in the fall?
The first fall frost around Cottage Grove, OR typically arrives about Nov 1. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Apr 12 on average, or Mar 18 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 205 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 97424 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026