Last spring frost
Jun 12
Frost Dates for Cooper Landing, AK
First fall frost
Sep 1
Growing season
78 days
In an average year around Cooper Landing, AK, the last spring frost (32°F) is about Jun 12 and the first fall frost is about Sep 1, giving roughly a 78-day growing season. To be safe most years, wait until May 29 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 2 | Jun 12 | May 29 |
| Hard (28°F) | Jun 8 | May 26 | May 6 |
| Severe (24°F) | May 23 | May 4 | Apr 15 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jul 2 | Jun 24 | Jun 19 | Jun 15 | Jun 12 | Jun 9 | Jun 5 | Jun 2 | May 29 |
| 28°F | Jun 8 | Jun 2 | May 31 | May 28 | May 26 | May 23 | May 19 | May 13 | May 6 |
| 24°F | May 23 | May 17 | May 12 | May 8 | May 4 | May 1 | Apr 28 | Apr 23 | Apr 15 |
| 20°F | May 4 | Apr 30 | Apr 27 | Apr 21 | Apr 17 | Apr 13 | Apr 10 | Apr 6 | Apr 2 |
| 16°F | Apr 24 | Apr 18 | Apr 13 | Apr 10 | Apr 7 | Apr 4 | Apr 2 | Mar 31 | Mar 27 |
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) | Aug 14 | Sep 1 | Sep 17 |
| Hard (28°F) | Aug 31 | Sep 15 | Sep 30 |
| Severe (24°F) | Sep 11 | Sep 29 | Oct 16 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 14 | Aug 21 | Aug 26 | Aug 30 | Sep 1 | Sep 4 | Sep 6 | Sep 11 | Sep 17 |
| 28°F | Aug 31 | Sep 3 | Sep 7 | Sep 11 | Sep 15 | Sep 18 | Sep 22 | Sep 26 | Sep 30 |
| 24°F | Sep 11 | Sep 19 | Sep 23 | Sep 27 | Sep 29 | Oct 1 | Oct 4 | Oct 10 | Oct 16 |
| 20°F | Sep 24 | Sep 30 | Oct 2 | Oct 5 | Oct 9 | Oct 13 | Oct 17 | Oct 22 | Oct 28 |
| 16°F | Oct 1 | Oct 6 | Oct 11 | Oct 17 | Oct 20 | Oct 24 | Oct 28 | Nov 1 | Nov 6 |
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: Cooper Landing 5 W, Ak, about 3 miles away@if(!empty($station['elevation_ft'])), at 375 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 Cooper Landing, AK?
On average, the last spring frost (32°F) around Cooper Landing, AK is about Jun 12. In cooler years it can run later, so for a safer bet many gardeners wait until May 29.
When is the first frost in the fall?
The first fall frost around Cooper Landing, AK typically arrives about Sep 1. 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 Jun 12 on average, or May 29 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 78 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 99572 Planting calendar → Alaska frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026