Last spring frost
May 9
Frost Dates for Sitka, AK
First fall frost
Oct 4
Growing season
145 days
In an average year around Sitka, AK, the last spring frost (32°F) is about May 9 and the first fall frost is about Oct 4, giving roughly a 145-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%) |
|---|---|---|---|
| Freeze (32°F) | Jul 4 | May 9 | Apr 25 |
| Hard (28°F) | Jul 3 | Apr 26 | Apr 3 |
| Severe (24°F) | Jun 25 | Apr 9 | Mar 12 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jul 4 | Jun 3 | May 19 | May 13 | May 9 | May 5 | May 2 | Apr 30 | Apr 25 |
| 28°F | Jul 3 | May 31 | May 8 | May 1 | Apr 26 | Apr 21 | Apr 15 | Apr 10 | Apr 3 |
| 24°F | Jun 25 | May 14 | Apr 29 | Apr 18 | Apr 9 | Apr 2 | Mar 28 | Mar 21 | Mar 12 |
| 20°F | Apr 29 | Apr 7 | Mar 28 | Mar 21 | Mar 17 | Mar 12 | Mar 7 | Mar 1 | Feb 17 |
| 16°F | Mar 24 | Mar 16 | Mar 10 | Mar 6 | Mar 1 | Feb 23 | Feb 11 | Feb 2 | Jan 19 |
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%) |
|---|---|---|---|
| Freeze (32°F) | Sep 1 | Oct 4 | Oct 26 |
| Hard (28°F) | Sep 2 | Oct 19 | Nov 15 |
| Severe (24°F) | Sep 7 | Nov 8 | Nov 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Sep 1 | Sep 18 | Sep 26 | Sep 30 | Oct 4 | Oct 8 | Oct 14 | Oct 19 | Oct 26 |
| 28°F | Sep 2 | Sep 24 | Oct 2 | Oct 10 | Oct 19 | Oct 28 | Nov 3 | Nov 8 | Nov 15 |
| 24°F | Sep 7 | Sep 29 | Oct 9 | Oct 28 | Nov 8 | Nov 13 | Nov 18 | Nov 22 | Nov 28 |
| 20°F | Oct 1 | Nov 1 | Nov 14 | Nov 20 | Nov 25 | Nov 29 | Dec 4 | Dec 14 | Dec 27 |
| 16°F | Nov 23 | Nov 30 | Dec 4 | Dec 11 | Dec 21 | Dec 28 | Jan 4 | Jan 13 | Jan 25 |
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: Hoonah, Ak, about 11 miles away@if(!empty($station['elevation_ft'])), at 130 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 Sitka, AK?
On average, the last spring frost (32°F) around Sitka, AK 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 Sitka, AK typically arrives about Oct 4. 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 145 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 99841 Planting calendar → Alaska frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026