Frost dates for 99519Anchorage, AK
The average last spring frost in Anchorage is May 18 and the average first fall frost is September 23, giving a typical growing season of about 125 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 18
- Average first fall frost
- Sep 23
- Growing season
- 125 days
Safer after May 31 (1-in-10 risk)
Possible by Sep 8 (1-in-10 risk)
Last frost typically in 204 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 21 · Jun 5 · Jun 20 | Aug 25 · Sep 11 · Sep 24 | 96 days | 100% |
| Frost / freeze (32°F) | May 4 · May 18 · May 31 | Sep 8 · Sep 23 · Oct 6 | 125 days | 100% |
| Hard freeze (28°F) | Apr 17 · May 4 · May 17 | Sep 20 · Oct 2 · Oct 17 | 151 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 17 – Jun 23 |
| Tomatoes | Transplant outdoors | Jun 3 – Jun 3 |
| Peppers | Start seeds indoors | Apr 17 – May 18 |
| Peppers | Transplant outdoors | Jun 17 – Jul 18 |
| Eggplant | Start seeds indoors | May 4 – Jun 2 |
| Eggplant | Transplant outdoors | Jun 17 – Jul 18 |
| Cucumbers | Sow outdoors | Jun 17 – Jun 13 |
| Summer squash | Sow outdoors | Jun 3 – Jul 18 |
| Winter squash & pumpkins | Sow outdoors | Jun 17 – Jul 18 |
| Snap beans | Sow outdoors | Jun 3 – Jul 6 |
| Sweet corn | Sow outdoors | Jun 3 – Jun 3 |
| Watermelon & cantaloupe | Sow outdoors | Jun 17 – Jul 18 |
| Okra | Sow outdoors | Jun 10 – Jul 3 |
| Peas | Sow outdoors (spring) | Apr 17 – Jun 2 |
| Potatoes | Plant outdoors (spring) | Apr 17 – Jun 17 |
| Onions | Start seeds indoors (spring) | Mar 6 – Apr 2 |
| Onions | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (spring) | Mar 30 – May 3 |
| Broccoli | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (fall) | May 24 – Jun 3 |
| Broccoli | Transplant outdoors (fall) | Jun 23 – Jul 4 |
| Cabbage | Start seeds indoors (spring) | Mar 20 – Apr 17 |
| Cabbage | Transplant outdoors (spring) | Apr 17 – May 18 |
| Cabbage | Start seeds indoors (fall) | May 14 – Jun 13 |
| Cabbage | Transplant outdoors (fall) | Jun 13 – Jul 14 |
| Leaf lettuce | Sow outdoors (spring) | Apr 17 – Jul 3 |
| Leaf lettuce | Sow outdoors (fall) | Jun 13 – Jul 30 |
| Spinach | Sow outdoors (spring) | Apr 10 – May 24 |
| Spinach | Sow outdoors (fall) | Jun 30 – Aug 4 |
| Radishes | Sow outdoors (spring) | Apr 17 – Jun 7 |
| Radishes | Sow outdoors (fall) | Jun 13 – Aug 14 |
| Kale | Sow outdoors (spring) | May 4 – May 24 |
| Kale | Sow outdoors (fall) | Jun 6 – Jul 14 |
| Carrots | Sow outdoors (spring) | May 18 – Jul 3 |
| Carrots | Sow outdoors (fall) | May 14 – Jun 29 |
| Garlic | Plant outdoors (fall) | Sep 13 – Oct 14 |
Where these dates come from
ZIP code 99519 is matched to the NOAA station Glen Alps, AK, 13.6 km away, at 2,202 ft elevation (826 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Glen Alps, AK (used) | 2,202 ft | May 18 | Sep 23 |
| Anchorage Upper De Armoun, AK | 1,335 ft | May 7 | Sep 28 |
| Eagle Rvr Nature Ctr, AK | 520 ft | May 16 | Sep 20 |
| Anchorage Rabbit Creek #2, AK | 913 ft | May 12 | Sep 26 |
Frost dates near Anchorage
- Indian, AK 99540 · last May 18, first Sep 23
- Anchorage, AK 99695 · last May 18, first Sep 23
- Eagle River, AK 99577 · last May 9, first Sep 26
- Girdwood, AK 99587 · last May 8, first Sep 29
- Hope, AK 99605 · last May 18, first Sep 23
- Chugiak, AK 99567 · last May 21, first Sep 15
- Wasilla, AK 99687 · last May 14, first Sep 20
- Big Lake, AK 99652 · last May 29, first Sep 7
Frequently asked questions
- When is the last frost in Anchorage, AK?
- For ZIP code 99519, the average last spring frost (32°F) is May 18, based on NOAA 1991-2020 climate normals for the Glen Alps, AK weather station. There is a 1-in-10 chance of a frost after May 31.
- When is the first frost in Anchorage, AK?
- The average first fall frost (32°F) is September 23. There is a 1-in-10 chance of frost by September 8, so tender plants are at risk from that point on.
- How long is the growing season in 99519?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 125 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.