Frost dates for 99688Willow, AK
The average last spring frost in Willow is May 29 and the average first fall frost is September 7, giving a typical growing season of about 100 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 29
- Average first fall frost
- Sep 7
- Growing season
- 100 days
Safer after Jun 9 (1-in-10 risk)
Possible by Aug 24 (1-in-10 risk)
Last frost typically in 214 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) | — | — | 74 days | 100% |
| Frost / freeze (32°F) | May 13 · May 29 · Jun 9 | Aug 24 · Sep 7 · Sep 21 | 100 days | 100% |
| Hard freeze (28°F) | Apr 29 · May 14 · May 27 | Sep 3 · Sep 19 · Oct 2 | 127 days | 100% |
Planting calendar for Willow
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 28 – Jul 4 |
| Tomatoes | Transplant outdoors | Jun 14 – May 18 |
| Peppers | Start seeds indoors | Apr 28 – May 29 |
| Peppers | Transplant outdoors | Jun 28 – Jul 29 |
| Eggplant | Start seeds indoors | May 15 – Jun 13 |
| Eggplant | Transplant outdoors | Jun 28 – Jul 29 |
| Cucumbers | Sow outdoors | Jun 28 – May 28 |
| Summer squash | Sow outdoors | Jun 14 – Jul 29 |
| Winter squash & pumpkins | Sow outdoors | Jun 28 – Jul 29 |
| Snap beans | Sow outdoors | Jun 14 – Jun 20 |
| Sweet corn | Sow outdoors | Jun 14 – May 18 |
| Watermelon & cantaloupe | Sow outdoors | Jun 28 – Jul 29 |
| Okra | Sow outdoors | Jun 21 – Jul 14 |
| Peas | Sow outdoors (spring) | Apr 28 – Jun 13 |
| Potatoes | Plant outdoors (spring) | Apr 28 – Jun 28 |
| Onions | Start seeds indoors (spring) | Mar 17 – Apr 13 |
| Onions | Transplant outdoors (spring) | May 15 – Jun 13 |
| Broccoli | Start seeds indoors (spring) | Apr 10 – May 14 |
| Broccoli | Transplant outdoors (spring) | May 15 – Jun 13 |
| Broccoli | Start seeds indoors (fall) | May 8 – May 18 |
| Broccoli | Transplant outdoors (fall) | Jun 7 – Jun 18 |
| Cabbage | Start seeds indoors (spring) | Mar 31 – Apr 28 |
| Cabbage | Transplant outdoors (spring) | Apr 28 – May 29 |
| Cabbage | Start seeds indoors (fall) | Apr 28 – May 28 |
| Cabbage | Transplant outdoors (fall) | May 28 – Jun 28 |
| Leaf lettuce | Sow outdoors (spring) | Apr 28 – Jul 14 |
| Leaf lettuce | Sow outdoors (fall) | May 28 – Jul 14 |
| Spinach | Sow outdoors (spring) | Apr 21 – Jun 4 |
| Spinach | Sow outdoors (fall) | Jun 14 – Jul 19 |
| Radishes | Sow outdoors (spring) | Apr 28 – Jun 18 |
| Radishes | Sow outdoors (fall) | May 28 – Jul 29 |
| Kale | Sow outdoors (spring) | May 15 – Jun 4 |
| Kale | Sow outdoors (fall) | May 21 – Jun 28 |
| Carrots | Sow outdoors (spring) | May 29 – Jul 14 |
| Carrots | Sow outdoors (fall) | Apr 28 – Jun 13 |
| Garlic | Plant outdoors (fall) | Aug 28 – Sep 28 |
Where these dates come from
ZIP code 99688 is matched to the NOAA station Whites Crossing, AK, 21.1 km away, at 270 ft elevation (17 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Whites Crossing, AK (used) | 270 ft | May 29 | Sep 7 |
| Willow West, AK | 205 ft | May 15 | Sep 18 |
| Amber Lake, AK | 449 ft | May 28 | Sep 13 |
| Little Su At Hatcher Pass Brg, AK | 902 ft | May 18 | Sep 18 |
Frost dates near Willow
- Houston, AK 99694 · last May 29, first Sep 7
- Talkeetna, AK 99676 · last May 16, first Sep 16
- Big Lake, AK 99652 · last May 29, first Sep 7
- Wasilla, AK 99623 · last May 16, first Sep 23
- Trapper Creek, AK 99683 · last May 16, first Sep 16
- Palmer, AK 99645 · last May 22, first Sep 16
- Chugiak, AK 99567 · last May 21, first Sep 15
- Sutton, AK 99674 · last Jun 1, first Sep 6
Frequently asked questions
- When is the last frost in Willow, AK?
- For ZIP code 99688, the average last spring frost (32°F) is May 29, based on NOAA 1991-2020 climate normals for the Whites Crossing, AK weather station. There is a 1-in-10 chance of a frost after June 9.
- When is the first frost in Willow, AK?
- The average first fall frost (32°F) is September 7. 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 99688?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 100 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.