Frost dates for 99737Delta Junction, AK
The average last spring frost in Delta Junction is May 17 and the average first fall frost is September 7, giving a typical growing season of about 113 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 17
- Average first fall frost
- Sep 7
- Growing season
- 113 days
Safer after May 31 (1-in-10 risk)
Possible by Aug 23 (1-in-10 risk)
Last frost typically in 202 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 15 · May 29 · Jun 9 | Aug 13 · Aug 27 · Sep 9 | 91 days | 100% |
| Frost / freeze (32°F) | May 3 · May 17 · May 31 | Aug 23 · Sep 7 · Sep 22 | 113 days | 100% |
| Hard freeze (28°F) | Apr 23 · May 6 · May 24 | Sep 3 · Sep 20 · Oct 1 | 134 days | 100% |
Planting calendar for Delta Junction
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 16 – Jun 22 |
| Tomatoes | Transplant outdoors | Jun 2 – May 18 |
| Peppers | Start seeds indoors | Apr 16 – May 17 |
| Peppers | Transplant outdoors | Jun 16 – Jul 17 |
| Eggplant | Start seeds indoors | May 3 – Jun 1 |
| Eggplant | Transplant outdoors | Jun 16 – Jul 17 |
| Cucumbers | Sow outdoors | Jun 16 – May 28 |
| Summer squash | Sow outdoors | Jun 2 – Jul 17 |
| Winter squash & pumpkins | Sow outdoors | Jun 16 – Jul 17 |
| Snap beans | Sow outdoors | Jun 2 – Jun 20 |
| Sweet corn | Sow outdoors | Jun 2 – May 18 |
| Watermelon & cantaloupe | Sow outdoors | Jun 16 – Jul 17 |
| Okra | Sow outdoors | Jun 9 – Jul 2 |
| Peas | Sow outdoors (spring) | Apr 16 – Jun 1 |
| Potatoes | Plant outdoors (spring) | Apr 16 – Jun 16 |
| Onions | Start seeds indoors (spring) | Mar 5 – Apr 1 |
| Onions | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (spring) | Mar 29 – May 2 |
| Broccoli | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (fall) | May 8 – May 18 |
| Broccoli | Transplant outdoors (fall) | Jun 7 – Jun 18 |
| Cabbage | Start seeds indoors (spring) | Mar 19 – Apr 16 |
| Cabbage | Transplant outdoors (spring) | Apr 16 – May 17 |
| Cabbage | Start seeds indoors (fall) | Apr 28 – May 28 |
| Cabbage | Transplant outdoors (fall) | May 28 – Jun 28 |
| Leaf lettuce | Sow outdoors (spring) | Apr 16 – Jul 2 |
| Leaf lettuce | Sow outdoors (fall) | May 28 – Jul 14 |
| Spinach | Sow outdoors (spring) | Apr 9 – May 23 |
| Spinach | Sow outdoors (fall) | Jun 14 – Jul 19 |
| Radishes | Sow outdoors (spring) | Apr 16 – Jun 6 |
| Radishes | Sow outdoors (fall) | May 28 – Jul 29 |
| Kale | Sow outdoors (spring) | May 3 – May 23 |
| Kale | Sow outdoors (fall) | May 21 – Jun 28 |
| Carrots | Sow outdoors (spring) | May 17 – Jul 2 |
| Carrots | Sow outdoors (fall) | Apr 28 – Jun 13 |
| Garlic | Plant outdoors (fall) | Aug 28 – Sep 28 |
Where these dates come from
ZIP code 99737 is matched to the NOAA station Big Delta Ap, AK, 4.9 km away, at 1,277 ft elevation (109 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Big Delta Ap, AK (used) | 1,277 ft | May 17 | Sep 7 |
| Delta 5 Ne, AK | 1,060 ft | Jun 4 | Aug 22 |
| Delta 6 N, AK | 1,059 ft | — | — |
| Whitestone Farms, AK | 995 ft | May 26 | Sep 2 |
Frost dates near Delta Junction
- Fort Greely, AK 99731 · last May 17, first Sep 7
- Salcha, AK 99714 · last May 20, first Sep 1
- Two Rivers, AK 99716 · last May 30, first Sep 2
Frequently asked questions
- When is the last frost in Delta Junction, AK?
- For ZIP code 99737, the average last spring frost (32°F) is May 17, based on NOAA 1991-2020 climate normals for the Big Delta Ap, AK weather station. There is a 1-in-10 chance of a frost after May 31.
- When is the first frost in Delta Junction, AK?
- The average first fall frost (32°F) is September 7. There is a 1-in-10 chance of frost by August 23, so tender plants are at risk from that point on.
- How long is the growing season in 99737?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 113 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.