Frost dates for 99515Anchorage, AK
The average last spring frost in Anchorage is May 1 and the average first fall frost is October 3, giving a typical growing season of about 156 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 1
- Average first fall frost
- Oct 3
- Growing season
- 156 days
Safer after May 8 (1-in-10 risk)
Possible by Sep 22 (1-in-10 risk)
Last frost typically in 196 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 2 · May 9 · May 20 | Sep 12 · Sep 23 · Oct 5 | 135 days | 100% |
| Frost / freeze (32°F) | Apr 20 · May 1 · May 8 | Sep 22 · Oct 3 · Oct 16 | 156 days | 100% |
| Hard freeze (28°F) | Apr 11 · Apr 20 · May 1 | Oct 1 · Oct 14 · Oct 27 | 175 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 | Mar 31 – Jun 6 |
| Tomatoes | Transplant outdoors | May 17 – Jun 13 |
| Peppers | Start seeds indoors | Mar 31 – May 1 |
| Peppers | Transplant outdoors | May 31 – Jul 1 |
| Eggplant | Start seeds indoors | Apr 17 – May 16 |
| Eggplant | Transplant outdoors | May 31 – Jul 1 |
| Cucumbers | Sow outdoors | May 31 – Jun 23 |
| Summer squash | Sow outdoors | May 17 – Jul 1 |
| Winter squash & pumpkins | Sow outdoors | May 31 – Jul 1 |
| Snap beans | Sow outdoors | May 17 – Jul 16 |
| Sweet corn | Sow outdoors | May 17 – Jun 13 |
| Watermelon & cantaloupe | Sow outdoors | May 31 – Jul 1 |
| Okra | Sow outdoors | May 24 – Jun 16 |
| Peas | Sow outdoors (spring) | Mar 31 – May 16 |
| Potatoes | Plant outdoors (spring) | Mar 31 – May 31 |
| Onions | Start seeds indoors (spring) | Feb 17 – Mar 16 |
| Onions | Transplant outdoors (spring) | Apr 17 – May 16 |
| Broccoli | Start seeds indoors (spring) | Mar 13 – Apr 16 |
| Broccoli | Transplant outdoors (spring) | Apr 17 – May 16 |
| Broccoli | Start seeds indoors (fall) | Jun 3 – Jun 13 |
| Broccoli | Transplant outdoors (fall) | Jul 3 – Jul 14 |
| Cabbage | Start seeds indoors (spring) | Mar 3 – Mar 31 |
| Cabbage | Transplant outdoors (spring) | Mar 31 – May 1 |
| Cabbage | Start seeds indoors (fall) | May 24 – Jun 23 |
| Cabbage | Transplant outdoors (fall) | Jun 23 – Jul 24 |
| Leaf lettuce | Sow outdoors (spring) | Mar 31 – Jun 16 |
| Leaf lettuce | Sow outdoors (fall) | Jun 23 – Aug 9 |
| Spinach | Sow outdoors (spring) | Mar 24 – May 7 |
| Spinach | Sow outdoors (fall) | Jul 10 – Aug 14 |
| Radishes | Sow outdoors (spring) | Mar 31 – May 21 |
| Radishes | Sow outdoors (fall) | Jun 23 – Aug 24 |
| Kale | Sow outdoors (spring) | Apr 17 – May 7 |
| Kale | Sow outdoors (fall) | Jun 16 – Jul 24 |
| Carrots | Sow outdoors (spring) | May 1 – Jun 16 |
| Carrots | Sow outdoors (fall) | May 24 – Jul 9 |
| Garlic | Plant outdoors (fall) | Sep 23 – Oct 24 |
Where these dates come from
ZIP code 99515 is matched to the NOAA station Anchorage Lake Hood Ap, AK, 7.5 km away, at 90 ft elevation (14 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Anchorage Lake Hood Ap, AK (used) | 90 ft | May 1 | Oct 3 |
| Anchorage Forecast Office, AK | 131 ft | May 5 | Sep 29 |
| Campbell Creek Sci Ctr, AK | 258 ft | May 28 | Sep 12 |
| Anchorage Rabbit Creek #2, AK | 913 ft | May 12 | Sep 26 |
Frost dates near Anchorage
- Anchorage, AK 99510 · last May 1, first Oct 3
- 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 99623 · last May 16, first Sep 23
Frequently asked questions
- When is the last frost in Anchorage, AK?
- For ZIP code 99515, the average last spring frost (32°F) is May 1, based on NOAA 1991-2020 climate normals for the Anchorage Lake Hood Ap, AK weather station. There is a 1-in-10 chance of a frost after May 8.
- When is the first frost in Anchorage, AK?
- The average first fall frost (32°F) is October 3. There is a 1-in-10 chance of frost by September 22, so tender plants are at risk from that point on.
- How long is the growing season in 99515?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 156 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.