Frost dates for 99635Nikiski, AK
The average last spring frost in Nikiski is May 18 and the average first fall frost is September 22, 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 22
- Growing season
- 125 days
Safer after May 30 (1-in-10 risk)
Possible by Sep 6 (1-in-10 risk)
Last frost typically in 203 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 2 · Jun 15 | Aug 26 · Sep 10 · Sep 23 | 99 days | 100% |
| Frost / freeze (32°F) | May 5 · May 18 · May 30 | Sep 6 · Sep 22 · Oct 5 | 125 days | 100% |
| Hard freeze (28°F) | Apr 20 · May 5 · May 18 | Sep 19 · Oct 2 · Oct 17 | 149 days | 100% |
Planting calendar for Nikiski
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 2 |
| 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 12 |
| Summer squash | Sow outdoors | Jun 3 – Jul 18 |
| Winter squash & pumpkins | Sow outdoors | Jun 17 – Jul 18 |
| Snap beans | Sow outdoors | Jun 3 – Jul 5 |
| Sweet corn | Sow outdoors | Jun 3 – Jun 2 |
| 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 23 – Jun 2 |
| Broccoli | Transplant outdoors (fall) | Jun 22 – Jul 3 |
| Cabbage | Start seeds indoors (spring) | Mar 20 – Apr 17 |
| Cabbage | Transplant outdoors (spring) | Apr 17 – May 18 |
| Cabbage | Start seeds indoors (fall) | May 13 – Jun 12 |
| Cabbage | Transplant outdoors (fall) | Jun 12 – Jul 13 |
| Leaf lettuce | Sow outdoors (spring) | Apr 17 – Jul 3 |
| Leaf lettuce | Sow outdoors (fall) | Jun 12 – Jul 29 |
| Spinach | Sow outdoors (spring) | Apr 10 – May 24 |
| Spinach | Sow outdoors (fall) | Jun 29 – Aug 3 |
| Radishes | Sow outdoors (spring) | Apr 17 – Jun 7 |
| Radishes | Sow outdoors (fall) | Jun 12 – Aug 13 |
| Kale | Sow outdoors (spring) | May 4 – May 24 |
| Kale | Sow outdoors (fall) | Jun 5 – Jul 13 |
| Carrots | Sow outdoors (spring) | May 18 – Jul 3 |
| Carrots | Sow outdoors (fall) | May 13 – Jun 28 |
| Garlic | Plant outdoors (fall) | Sep 12 – Oct 13 |
Where these dates come from
ZIP code 99635 is matched to the NOAA station Kenai 9N, AK, 4.3 km away, at 126 ft elevation (8 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Kenai 9N, AK (used) | 126 ft | May 18 | Sep 22 |
| Kenai Muni Ap, AK | 91 ft | May 24 | Sep 12 |
| Sterling 6Sw, AK | 292 ft | May 20 | Sep 21 |
| Soldotna 5Ssw, AK | 180 ft | Jun 11 | Sep 1 |
Frost dates near Nikiski
- Kenai, AK 99611 · last May 24, first Sep 12
- Soldotna, AK 99669 · last Jun 11, first Sep 1
- Sterling, AK 99672 · last May 20, first Sep 21
- Tyonek, AK 99682 · last May 18, first Sep 22
- Kasilof, AK 99610 · last Jun 11, first Sep 1
- Clam Gulch, AK 99568 · last Jun 11, first Sep 1
- Ninilchik, AK 99639 · last May 10, first Sep 29
- Anchor Point, AK 99556 · last May 27, first Sep 22
Frequently asked questions
- When is the last frost in Nikiski, AK?
- For ZIP code 99635, the average last spring frost (32°F) is May 18, based on NOAA 1991-2020 climate normals for the Kenai 9N, AK weather station. There is a 1-in-10 chance of a frost after May 30.
- When is the first frost in Nikiski, AK?
- The average first fall frost (32°F) is September 22. There is a 1-in-10 chance of frost by September 6, so tender plants are at risk from that point on.
- How long is the growing season in 99635?
- 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.