Frost dates for 99631Moose Pass, AK
The average last spring frost in Moose Pass is May 31 and the average first fall frost is September 8, giving a typical growing season of about 99 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 31
- Average first fall frost
- Sep 8
- Growing season
- 99 days
Safer after Jun 15 (1-in-10 risk)
Possible by Aug 24 (1-in-10 risk)
Last frost typically in 216 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) | — | — | 67 days | 100% |
| Frost / freeze (32°F) | May 19 · May 31 · Jun 15 | Aug 24 · Sep 8 · Sep 25 | 99 days | 100% |
| Hard freeze (28°F) | Apr 30 · May 14 · May 28 | Sep 4 · Sep 22 · Oct 6 | 129 days | 100% |
Planting calendar for Moose Pass
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 30 – Jul 6 |
| Tomatoes | Transplant outdoors | Jun 16 – May 19 |
| Peppers | Start seeds indoors | Apr 30 – May 31 |
| Peppers | Transplant outdoors | Jun 30 – Jul 31 |
| Eggplant | Start seeds indoors | May 17 – Jun 15 |
| Eggplant | Transplant outdoors | Jun 30 – Jul 31 |
| Cucumbers | Sow outdoors | Jun 30 – May 29 |
| Summer squash | Sow outdoors | Jun 16 – Jul 31 |
| Winter squash & pumpkins | Sow outdoors | Jun 30 – Jul 31 |
| Snap beans | Sow outdoors | Jun 16 – Jun 21 |
| Sweet corn | Sow outdoors | Jun 16 – May 19 |
| Watermelon & cantaloupe | Sow outdoors | Jun 30 – Jul 31 |
| Okra | Sow outdoors | Jun 23 – Jul 16 |
| Peas | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Potatoes | Plant outdoors (spring) | Apr 30 – Jun 30 |
| Onions | Start seeds indoors (spring) | Mar 19 – Apr 15 |
| Onions | Transplant outdoors (spring) | May 17 – Jun 15 |
| Broccoli | Start seeds indoors (spring) | Apr 12 – May 16 |
| Broccoli | Transplant outdoors (spring) | May 17 – Jun 15 |
| Broccoli | Start seeds indoors (fall) | May 9 – May 19 |
| Broccoli | Transplant outdoors (fall) | Jun 8 – Jun 19 |
| Cabbage | Start seeds indoors (spring) | Apr 2 – Apr 30 |
| Cabbage | Transplant outdoors (spring) | Apr 30 – May 31 |
| Cabbage | Start seeds indoors (fall) | Apr 29 – May 29 |
| Cabbage | Transplant outdoors (fall) | May 29 – Jun 29 |
| Leaf lettuce | Sow outdoors (spring) | Apr 30 – Jul 16 |
| Leaf lettuce | Sow outdoors (fall) | May 29 – Jul 15 |
| Spinach | Sow outdoors (spring) | Apr 23 – Jun 6 |
| Spinach | Sow outdoors (fall) | Jun 15 – Jul 20 |
| Radishes | Sow outdoors (spring) | Apr 30 – Jun 20 |
| Radishes | Sow outdoors (fall) | May 29 – Jul 30 |
| Kale | Sow outdoors (spring) | May 17 – Jun 6 |
| Kale | Sow outdoors (fall) | May 22 – Jun 29 |
| Carrots | Sow outdoors (spring) | May 31 – Jul 16 |
| Carrots | Sow outdoors (fall) | Apr 29 – Jun 14 |
| Garlic | Plant outdoors (fall) | Aug 29 – Sep 29 |
Where these dates come from
ZIP code 99631 is matched to the NOAA station Moose Pass 3Nw, AK, 12.5 km away, at 492 ft elevation (1,765 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Moose Pass 3Nw, AK (used) | 492 ft | May 31 | Sep 8 |
| Cooper Lake Project, AK | 505 ft | May 18 | Sep 27 |
| Seward 19N, AK | 518 ft | May 21 | Sep 26 |
| Hope, AK | 180 ft | May 18 | Sep 24 |
Frost dates near Moose Pass
- Cooper Landing, AK 99572 · last Jun 12, first Sep 1
- Hope, AK 99605 · last May 18, first Sep 23
- Girdwood, AK 99587 · last May 8, first Sep 29
- Whittier, AK 99693 · last Apr 25, first Oct 14
- Seward, AK 99664 · last May 2, first Oct 7
- 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
Frequently asked questions
- When is the last frost in Moose Pass, AK?
- For ZIP code 99631, the average last spring frost (32°F) is May 31, based on NOAA 1991-2020 climate normals for the Moose Pass 3Nw, AK weather station. There is a 1-in-10 chance of a frost after June 15.
- When is the first frost in Moose Pass, AK?
- The average first fall frost (32°F) is September 8. There is a 1-in-10 chance of frost by August 24, so tender plants are at risk from that point on.
- How long is the growing season in 99631?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 99 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.