Frost dates for 99516Anchorage, AK
The average last spring frost in Anchorage is May 12 and the average first fall frost is September 26, giving a typical growing season of about 137 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 12
- Average first fall frost
- Sep 26
- Growing season
- 137 days
Safer after May 24 (1-in-10 risk)
Possible by Sep 12 (1-in-10 risk)
Last frost typically in 193 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 15 · May 27 · Jun 5 | Aug 31 · Sep 15 · Sep 28 | 109 days | 100% |
| Frost / freeze (32°F) | Apr 30 · May 12 · May 24 | Sep 12 · Sep 26 · Oct 9 | 137 days | 100% |
| Hard freeze (28°F) | Apr 12 · Apr 29 · May 10 | Sep 24 · Oct 6 · Oct 20 | 161 days | 100% |
Planting calendar for Anchorage
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 11 – Jun 17 |
| Tomatoes | Transplant outdoors | May 28 – Jun 6 |
| Peppers | Start seeds indoors | Apr 11 – May 12 |
| Peppers | Transplant outdoors | Jun 11 – Jul 12 |
| Eggplant | Start seeds indoors | Apr 28 – May 27 |
| Eggplant | Transplant outdoors | Jun 11 – Jul 12 |
| Cucumbers | Sow outdoors | Jun 11 – Jun 16 |
| Summer squash | Sow outdoors | May 28 – Jul 12 |
| Winter squash & pumpkins | Sow outdoors | Jun 11 – Jul 12 |
| Snap beans | Sow outdoors | May 28 – Jul 9 |
| Sweet corn | Sow outdoors | May 28 – Jun 6 |
| Watermelon & cantaloupe | Sow outdoors | Jun 11 – Jul 12 |
| Okra | Sow outdoors | Jun 4 – Jun 27 |
| Peas | Sow outdoors (spring) | Apr 11 – May 27 |
| Potatoes | Plant outdoors (spring) | Apr 11 – Jun 11 |
| Onions | Start seeds indoors (spring) | Feb 28 – Mar 27 |
| Onions | Transplant outdoors (spring) | Apr 28 – May 27 |
| Broccoli | Start seeds indoors (spring) | Mar 24 – Apr 27 |
| Broccoli | Transplant outdoors (spring) | Apr 28 – May 27 |
| Broccoli | Start seeds indoors (fall) | May 27 – Jun 6 |
| Broccoli | Transplant outdoors (fall) | Jun 26 – Jul 7 |
| Cabbage | Start seeds indoors (spring) | Mar 14 – Apr 11 |
| Cabbage | Transplant outdoors (spring) | Apr 11 – May 12 |
| Cabbage | Start seeds indoors (fall) | May 17 – Jun 16 |
| Cabbage | Transplant outdoors (fall) | Jun 16 – Jul 17 |
| Leaf lettuce | Sow outdoors (spring) | Apr 11 – Jun 27 |
| Leaf lettuce | Sow outdoors (fall) | Jun 16 – Aug 2 |
| Spinach | Sow outdoors (spring) | Apr 4 – May 18 |
| Spinach | Sow outdoors (fall) | Jul 3 – Aug 7 |
| Radishes | Sow outdoors (spring) | Apr 11 – Jun 1 |
| Radishes | Sow outdoors (fall) | Jun 16 – Aug 17 |
| Kale | Sow outdoors (spring) | Apr 28 – May 18 |
| Kale | Sow outdoors (fall) | Jun 9 – Jul 17 |
| Carrots | Sow outdoors (spring) | May 12 – Jun 27 |
| Carrots | Sow outdoors (fall) | May 17 – Jul 2 |
| Garlic | Plant outdoors (fall) | Sep 16 – Oct 17 |
Where these dates come from
ZIP code 99516 is matched to the NOAA station Anchorage Rabbit Creek #2, AK, 2.3 km away, at 913 ft elevation (191 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Anchorage Rabbit Creek #2, AK (used) | 913 ft | May 12 | Sep 26 |
| Anchorage Upper De Armoun, AK | 1,335 ft | May 7 | Sep 28 |
| Glen Alps, AK | 2,202 ft | May 18 | Sep 23 |
| Campbell Creek Sci Ctr, AK | 258 ft | May 28 | Sep 12 |
Frost dates near Anchorage
- Anchorage, AK 99511 · last May 5, first Sep 29
- Indian, AK 99540 · last May 18, first Sep 23
- Eagle River, AK 99577 · last May 9, first Sep 26
- Hope, AK 99605 · last May 18, first Sep 23
- Chugiak, AK 99567 · last May 21, first Sep 15
- Girdwood, AK 99587 · last May 8, first Sep 29
- Big Lake, AK 99652 · last May 29, first Sep 7
- Wasilla, AK 99687 · last May 14, first Sep 20
Frequently asked questions
- When is the last frost in Anchorage, AK?
- For ZIP code 99516, the average last spring frost (32°F) is May 12, based on NOAA 1991-2020 climate normals for the Anchorage Rabbit Creek #2, AK weather station. There is a 1-in-10 chance of a frost after May 24.
- When is the first frost in Anchorage, AK?
- The average first fall frost (32°F) is September 26. There is a 1-in-10 chance of frost by September 12, so tender plants are at risk from that point on.
- How long is the growing season in 99516?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 137 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.