Last spring frost
Mar 27
Frost Dates for Boring, OR
First fall frost
Nov 18
Growing season
239 days
Hardiness zone
8b
In an average year around Boring, OR, the last spring frost (32°F) is about Mar 27 and the first fall frost is about Nov 18, giving roughly a 239-day growing season. To be safe most years, wait until Feb 26 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 12 | Apr 26 | Apr 7 |
| Freeze (32°F) | Apr 20 | Mar 27 | Feb 26 |
| Hard (28°F) | Mar 12 | Feb 14 | Jan 2 |
| Severe (24°F) | Feb 21 | Jan 16 | Dec 9 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 12 | May 6 | May 2 | Apr 30 | Apr 26 | Apr 22 | Apr 19 | Apr 14 | Apr 7 |
| 32°F | Apr 20 | Apr 10 | Apr 3 | Mar 30 | Mar 27 | Mar 21 | Mar 13 | Mar 5 | Feb 26 |
| 28°F | Mar 12 | Mar 3 | Feb 25 | Feb 20 | Feb 14 | Feb 6 | Jan 30 | Jan 19 | Jan 2 |
| 24°F | Feb 21 | Feb 13 | Feb 3 | Jan 26 | Jan 16 | Jan 6 | Dec 31 | Dec 21 | Dec 9 |
| 20°F | Feb 21 | Feb 8 | Jan 23 | Jan 11 | Jan 1 | Dec 26 | Dec 19 | Dec 11 | Dec 3 |
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 12 | Oct 29 | Nov 18 |
| Freeze (32°F) | Oct 26 | Nov 18 | Dec 10 |
| Hard (28°F) | Nov 12 | Dec 9 | Jan 19 |
| Severe (24°F) | Nov 29 | Dec 29 | Feb 9 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 12 | Oct 18 | Oct 21 | Oct 24 | Oct 29 | Nov 1 | Nov 5 | Nov 10 | Nov 18 |
| 32°F | Oct 26 | Nov 3 | Nov 8 | Nov 13 | Nov 18 | Nov 24 | Nov 29 | Dec 3 | Dec 10 |
| 28°F | Nov 12 | Nov 22 | Nov 30 | Dec 3 | Dec 9 | Dec 15 | Dec 24 | Jan 2 | Jan 19 |
| 24°F | Nov 29 | Dec 5 | Dec 13 | Dec 21 | Dec 29 | Jan 3 | Jan 13 | Jan 25 | Feb 9 |
| 20°F | Dec 1 | Dec 7 | Dec 13 | Dec 19 | Dec 24 | Jan 1 | Jan 13 | Jan 31 | Feb 17 |
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: Headworks Portland Wtr B, Or, about 8.8 miles away@if(!empty($station['elevation_ft'])), at 748 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 Boring, OR?
On average, the last spring frost (32°F) around Boring, OR is about Mar 27. In cooler years it can run later, so for a safer bet many gardeners wait until Feb 26.
When is the first frost in the fall?
The first fall frost around Boring, OR typically arrives about Nov 18. 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 27 on average, or Feb 26 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 239 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 97009 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026