Last spring frost
May 9
Frost Dates for Monument, OR
First fall frost
Sep 27
Growing season
139 days
Hardiness zone
7a
In an average year around Monument, OR, the last spring frost (32°F) is about May 9 and the first fall frost is about Sep 27, giving roughly a 139-day growing season. To be safe most years, wait until Apr 25 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) | Jun 20 | May 30 | May 11 |
| Freeze (32°F) | May 26 | May 9 | Apr 25 |
| Hard (28°F) | May 8 | Apr 23 | Apr 4 |
| Severe (24°F) | Apr 24 | Apr 2 | Mar 12 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 20 | Jun 14 | Jun 8 | Jun 3 | May 30 | May 26 | May 22 | May 16 | May 11 |
| 32°F | May 26 | May 18 | May 14 | May 12 | May 9 | May 6 | May 3 | Apr 29 | Apr 25 |
| 28°F | May 8 | May 3 | Apr 30 | Apr 27 | Apr 23 | Apr 20 | Apr 17 | Apr 12 | Apr 4 |
| 24°F | Apr 24 | Apr 17 | Apr 11 | Apr 6 | Apr 2 | Mar 30 | Mar 26 | Mar 20 | Mar 12 |
| 20°F | Apr 6 | Mar 28 | Mar 21 | Mar 16 | Mar 12 | Mar 7 | Mar 2 | Feb 27 | Feb 20 |
| 16°F | Mar 13 | Mar 6 | Feb 28 | Feb 25 | Feb 22 | Feb 17 | Feb 12 | Feb 5 | Jan 26 |
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) | Aug 30 | Sep 12 | Sep 27 |
| Freeze (32°F) | Sep 9 | Sep 27 | Oct 10 |
| Hard (28°F) | Sep 25 | Oct 9 | Oct 27 |
| Severe (24°F) | Oct 5 | Oct 23 | Nov 11 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 30 | Sep 2 | Sep 6 | Sep 9 | Sep 12 | Sep 15 | Sep 19 | Sep 22 | Sep 27 |
| 32°F | Sep 9 | Sep 15 | Sep 20 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 10 |
| 28°F | Sep 25 | Sep 30 | Oct 3 | Oct 5 | Oct 9 | Oct 12 | Oct 16 | Oct 21 | Oct 27 |
| 24°F | Oct 5 | Oct 10 | Oct 15 | Oct 19 | Oct 23 | Oct 26 | Oct 30 | Nov 4 | Nov 11 |
| 20°F | Oct 20 | Oct 25 | Oct 30 | Nov 2 | Nov 6 | Nov 11 | Nov 15 | Nov 21 | Nov 27 |
| 16°F | Oct 29 | Nov 4 | Nov 10 | Nov 15 | Nov 21 | Nov 24 | Nov 28 | Dec 3 | Dec 12 |
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: Monument 2, Or, about 10.3 miles away@if(!empty($station['elevation_ft'])), at 1,995 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 Monument, OR?
On average, the last spring frost (32°F) around Monument, OR is about May 9. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 25.
When is the first frost in the fall?
The first fall frost around Monument, OR typically arrives about Sep 27. 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 May 9 on average, or Apr 25 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 139 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 97848 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026