Frost dates for 99835Sitka, AK
The average last spring frost in Sitka is May 3 and the average first fall frost is October 18, giving a typical growing season of about 166 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 3
- Average first fall frost
- Oct 18
- Growing season
- 166 days
Safer after May 19 (1-in-10 risk)
Possible by Oct 1 (1-in-10 risk)
Last frost typically in 183 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | May 6 · May 23 · Jun 4 | Sep 20 · Oct 2 · Oct 22 | 132 days | 100% |
| Frost / freeze (32°F) | Apr 16 · May 3 · May 19 | Oct 1 · Oct 18 · Nov 7 | 166 days | 100% |
| Hard freeze (28°F) | Mar 16 · Apr 7 · Apr 30 | Oct 19 · Nov 10 · Dec 2 | 212 days | 100% |
Planting calendar for Sitka
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 2 – Jun 8 |
| Tomatoes | Transplant outdoors | May 19 – Jun 28 |
| Peppers | Start seeds indoors | Apr 2 – May 3 |
| Peppers | Transplant outdoors | Jun 2 – Jul 3 |
| Eggplant | Start seeds indoors | Apr 19 – May 18 |
| Eggplant | Transplant outdoors | Jun 2 – Jul 3 |
| Cucumbers | Sow outdoors | Jun 2 – Jul 8 |
| Summer squash | Sow outdoors | May 19 – Jul 3 |
| Winter squash & pumpkins | Sow outdoors | Jun 2 – Jul 3 |
| Snap beans | Sow outdoors | May 19 – Jul 31 |
| Sweet corn | Sow outdoors | May 19 – Jun 28 |
| Watermelon & cantaloupe | Sow outdoors | Jun 2 – Jul 3 |
| Okra | Sow outdoors | May 26 – Jun 18 |
| Peas | Sow outdoors (spring) | Apr 2 – May 18 |
| Potatoes | Plant outdoors (spring) | Apr 2 – Jun 2 |
| Onions | Start seeds indoors (spring) | Feb 19 – Mar 18 |
| Onions | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (spring) | Mar 15 – Apr 18 |
| Broccoli | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (fall) | Jun 18 – Jun 28 |
| Broccoli | Transplant outdoors (fall) | Jul 18 – Jul 29 |
| Cabbage | Start seeds indoors (spring) | Mar 5 – Apr 2 |
| Cabbage | Transplant outdoors (spring) | Apr 2 – May 3 |
| Cabbage | Start seeds indoors (fall) | Jun 8 – Jul 8 |
| Cabbage | Transplant outdoors (fall) | Jul 8 – Aug 8 |
| Leaf lettuce | Sow outdoors (spring) | Apr 2 – Jun 18 |
| Leaf lettuce | Sow outdoors (fall) | Jul 8 – Aug 24 |
| Spinach | Sow outdoors (spring) | Mar 26 – May 9 |
| Spinach | Sow outdoors (fall) | Jul 25 – Aug 29 |
| Radishes | Sow outdoors (spring) | Apr 2 – May 23 |
| Radishes | Sow outdoors (fall) | Jul 8 – Sep 8 |
| Kale | Sow outdoors (spring) | Apr 19 – May 9 |
| Kale | Sow outdoors (fall) | Jul 1 – Aug 8 |
| Carrots | Sow outdoors (spring) | May 3 – Jun 18 |
| Carrots | Sow outdoors (fall) | Jun 8 – Jul 24 |
| Garlic | Plant outdoors (fall) | Oct 8 – Nov 8 |
Where these dates come from
ZIP code 99835 is matched to the NOAA station Sitka 1 Ne, AK, 0.9 km away, at 78 ft elevation (6 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Sitka 1 Ne, AK (used) | 78 ft | May 3 | Oct 18 |
| Sitka Airport, AK | 14 ft | Apr 12 | Nov 1 |
| Hidden Falls Hatchery, AK | 22 ft | Apr 29 | Oct 25 |
| Little Port Walter, AK | 14 ft | Apr 21 | Oct 31 |
Frost dates near Sitka
- Angoon, AK 99820 · last Apr 29, first Oct 25
- Tenakee Springs, AK 99841 · last May 9, first Oct 4
- Port Alexander, AK 99836 · last Apr 18, first Nov 5
- Pelican, AK 99832 · last May 4, first Oct 19
Frequently asked questions
- When is the last frost in Sitka, AK?
- For ZIP code 99835, the average last spring frost (32°F) is May 3, based on NOAA 1991-2020 climate normals for the Sitka 1 Ne, AK weather station. There is a 1-in-10 chance of a frost after May 19.
- When is the first frost in Sitka, AK?
- The average first fall frost (32°F) is October 18. There is a 1-in-10 chance of frost by October 1, so tender plants are at risk from that point on.
- How long is the growing season in 99835?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 166 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.