Frost dates for 99529Anchorage, AK
The average last spring frost in Anchorage is May 5 and the average first fall frost is September 29, giving a typical growing season of about 147 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 5
- Average first fall frost
- Sep 29
- Growing season
- 147 days
Safer after May 14 (1-in-10 risk)
Possible by Sep 17 (1-in-10 risk)
Last frost typically in 190 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 8 · May 17 · May 28 | Sep 6 · Sep 19 · Oct 1 | 123 days | 100% |
| Frost / freeze (32°F) | Apr 25 · May 5 · May 14 | Sep 17 · Sep 29 · Oct 13 | 147 days | 100% |
| Hard freeze (28°F) | Apr 11 · Apr 22 · May 3 | Sep 27 · Oct 9 · Oct 23 | 169 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 4 – Jun 10 |
| Tomatoes | Transplant outdoors | May 21 – Jun 9 |
| Peppers | Start seeds indoors | Apr 4 – May 5 |
| Peppers | Transplant outdoors | Jun 4 – Jul 5 |
| Eggplant | Start seeds indoors | Apr 21 – May 20 |
| Eggplant | Transplant outdoors | Jun 4 – Jul 5 |
| Cucumbers | Sow outdoors | Jun 4 – Jun 19 |
| Summer squash | Sow outdoors | May 21 – Jul 5 |
| Winter squash & pumpkins | Sow outdoors | Jun 4 – Jul 5 |
| Snap beans | Sow outdoors | May 21 – Jul 12 |
| Sweet corn | Sow outdoors | May 21 – Jun 9 |
| Watermelon & cantaloupe | Sow outdoors | Jun 4 – Jul 5 |
| Okra | Sow outdoors | May 28 – Jun 20 |
| Peas | Sow outdoors (spring) | Apr 4 – May 20 |
| Potatoes | Plant outdoors (spring) | Apr 4 – Jun 4 |
| Onions | Start seeds indoors (spring) | Feb 21 – Mar 20 |
| Onions | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (spring) | Mar 17 – Apr 20 |
| Broccoli | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (fall) | May 30 – Jun 9 |
| Broccoli | Transplant outdoors (fall) | Jun 29 – Jul 10 |
| Cabbage | Start seeds indoors (spring) | Mar 7 – Apr 4 |
| Cabbage | Transplant outdoors (spring) | Apr 4 – May 5 |
| Cabbage | Start seeds indoors (fall) | May 20 – Jun 19 |
| Cabbage | Transplant outdoors (fall) | Jun 19 – Jul 20 |
| Leaf lettuce | Sow outdoors (spring) | Apr 4 – Jun 20 |
| Leaf lettuce | Sow outdoors (fall) | Jun 19 – Aug 5 |
| Spinach | Sow outdoors (spring) | Mar 28 – May 11 |
| Spinach | Sow outdoors (fall) | Jul 6 – Aug 10 |
| Radishes | Sow outdoors (spring) | Apr 4 – May 25 |
| Radishes | Sow outdoors (fall) | Jun 19 – Aug 20 |
| Kale | Sow outdoors (spring) | Apr 21 – May 11 |
| Kale | Sow outdoors (fall) | Jun 12 – Jul 20 |
| Carrots | Sow outdoors (spring) | May 5 – Jun 20 |
| Carrots | Sow outdoors (fall) | May 20 – Jul 5 |
| Garlic | Plant outdoors (fall) | Sep 19 – Oct 20 |
Where these dates come from
ZIP code 99529 is matched to the NOAA station Anchorage Forecast Office, AK, 2.2 km away, at 131 ft elevation (6 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Anchorage Forecast Office, AK (used) | 131 ft | May 5 | Sep 29 |
| Anchorage Lake Hood Ap, AK | 90 ft | May 1 | Oct 3 |
| Anchorage Intl Ap, AK | 120 ft | May 5 | Oct 1 |
| Anchorage Merrill Fld, AK | 138 ft | May 1 | Sep 29 |
Frost dates near Anchorage
- Anchorage, AK 99530 · 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
- Chugiak, AK 99567 · last May 21, first Sep 15
- Hope, AK 99605 · last May 18, first Sep 23
- Big Lake, AK 99652 · last May 29, first Sep 7
- Wasilla, AK 99623 · last May 16, first Sep 23
- Girdwood, AK 99587 · last May 8, first Sep 29
Frequently asked questions
- When is the last frost in Anchorage, AK?
- For ZIP code 99529, the average last spring frost (32°F) is May 5, based on NOAA 1991-2020 climate normals for the Anchorage Forecast Office, AK weather station. There is a 1-in-10 chance of a frost after May 14.
- When is the first frost in Anchorage, AK?
- The average first fall frost (32°F) is September 29. There is a 1-in-10 chance of frost by September 17, so tender plants are at risk from that point on.
- How long is the growing season in 99529?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 147 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.