Last spring frost
Apr 30
Frost Dates for Okanogan, WA
First fall frost
Oct 7
Growing season
160 days
Hardiness zone
7a
In an average year around Okanogan, WA, the last spring frost (32°F) is about Apr 30 and the first fall frost is about Oct 7, giving roughly a 160-day growing season. To be safe most years, wait until Apr 14 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 1 | May 13 | Apr 28 |
| Freeze (32°F) | May 15 | Apr 30 | Apr 14 |
| Hard (28°F) | May 2 | Apr 14 | Mar 26 |
| Severe (24°F) | Apr 14 | Mar 24 | Mar 4 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 1 | May 25 | May 21 | May 17 | May 13 | May 10 | May 6 | May 2 | Apr 28 |
| 32°F | May 15 | May 10 | May 6 | May 2 | Apr 30 | Apr 27 | Apr 24 | Apr 20 | Apr 14 |
| 28°F | May 2 | Apr 27 | Apr 23 | Apr 18 | Apr 14 | Apr 10 | Apr 5 | Apr 1 | Mar 26 |
| 24°F | Apr 14 | Apr 6 | Apr 1 | Mar 28 | Mar 24 | Mar 18 | Mar 13 | Mar 8 | Mar 4 |
| 20°F | Mar 19 | Mar 12 | Mar 7 | Mar 3 | Feb 28 | Feb 26 | Feb 22 | Feb 17 | Feb 10 |
| 16°F | Mar 6 | Feb 28 | Feb 25 | Feb 22 | Feb 17 | Feb 13 | Feb 8 | Feb 1 | Jan 20 |
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) | Sep 12 | Sep 28 | Oct 11 |
| Freeze (32°F) | Sep 23 | Oct 7 | Oct 22 |
| Hard (28°F) | Oct 3 | Oct 19 | Nov 4 |
| Severe (24°F) | Oct 13 | Oct 30 | Nov 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 17 | Sep 22 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 11 |
| 32°F | Sep 23 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 17 | Oct 22 |
| 28°F | Oct 3 | Oct 7 | Oct 11 | Oct 15 | Oct 19 | Oct 22 | Oct 26 | Oct 30 | Nov 4 |
| 24°F | Oct 13 | Oct 19 | Oct 23 | Oct 27 | Oct 30 | Nov 2 | Nov 6 | Nov 10 | Nov 18 |
| 20°F | Oct 22 | Oct 30 | Nov 3 | Nov 7 | Nov 12 | Nov 16 | Nov 20 | Nov 25 | Dec 2 |
| 16°F | Oct 31 | Nov 9 | Nov 15 | Nov 21 | Nov 25 | Nov 30 | Dec 4 | Dec 10 | Dec 19 |
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: Omak Ap, Wa, about 11.7 miles away@if(!empty($station['elevation_ft'])), at 1,296 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 Okanogan, WA?
On average, the last spring frost (32°F) around Okanogan, WA is about Apr 30. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 14.
When is the first frost in the fall?
The first fall frost around Okanogan, WA typically arrives about Oct 7. 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 30 on average, or Apr 14 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 160 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 98840 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026