Last spring frost
Mar 26
Frost Dates for Warrenton, OR
First fall frost
Nov 11
Growing season
232 days
Hardiness zone
9a
In an average year around Warrenton, OR, the last spring frost (32°F) is about Mar 26 and the first fall frost is about Nov 11, giving roughly a 232-day growing season. To be safe most years, wait until Feb 27 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 10 | Apr 25 | Apr 3 |
| Freeze (32°F) | Apr 18 | Mar 26 | Feb 27 |
| Hard (28°F) | Mar 17 | Feb 18 | Dec 31 |
| Severe (24°F) | Feb 21 | Jan 11 | Dec 2 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 10 | May 4 | May 1 | Apr 28 | Apr 25 | Apr 21 | Apr 17 | Apr 11 | Apr 3 |
| 32°F | Apr 18 | Apr 9 | Apr 3 | Mar 29 | Mar 26 | Mar 20 | Mar 14 | Mar 7 | Feb 27 |
| 28°F | Mar 17 | Mar 6 | Feb 28 | Feb 23 | Feb 18 | Feb 13 | Feb 3 | Jan 19 | Dec 31 |
| 24°F | Feb 21 | Feb 13 | Feb 3 | Jan 24 | Jan 11 | Jan 3 | Dec 23 | Dec 11 | Dec 2 |
| 20°F | Feb 14 | Feb 1 | Jan 14 | Jan 3 | Dec 27 | Dec 21 | Dec 13 | Dec 9 | Dec 7 |
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 5 | Oct 23 | Nov 11 |
| Freeze (32°F) | Oct 22 | Nov 11 | Dec 8 |
| Hard (28°F) | Nov 9 | Dec 5 | Jan 30 |
| Severe (24°F) | Nov 24 | Dec 20 | Feb 10 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 10 | Oct 16 | Oct 20 | Oct 23 | Oct 26 | Oct 30 | Nov 4 | Nov 11 |
| 32°F | Oct 22 | Oct 29 | Nov 2 | Nov 6 | Nov 11 | Nov 16 | Nov 22 | Nov 29 | Dec 8 |
| 28°F | Nov 9 | Nov 16 | Nov 24 | Dec 1 | Dec 5 | Dec 12 | Dec 25 | Jan 5 | Jan 30 |
| 24°F | Nov 24 | Dec 1 | Dec 7 | Dec 11 | Dec 20 | Jan 1 | Jan 11 | Jan 30 | Feb 10 |
| 20°F | Dec 2 | Dec 7 | Dec 11 | Dec 15 | Dec 21 | Dec 30 | Jan 7 | Jan 24 | Feb 13 |
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: Astoria Rgnl Ap, Or, about 5.7 miles away@if(!empty($station['elevation_ft'])), at 9 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 Warrenton, OR?
On average, the last spring frost (32°F) around Warrenton, OR is about Mar 26. In cooler years it can run later, so for a safer bet many gardeners wait until Feb 27.
When is the first frost in the fall?
The first fall frost around Warrenton, OR typically arrives about Nov 11. 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 Mar 26 on average, or Feb 27 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 232 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 97121 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026