Frost dates for ZIP 99645 (Knik River, AK)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Lazy Mtn, AK (2 miles away).
- Average last spring frostMay 2250% chance of a 32°F freeze after this date
- Average first fall frostSep 1650% chance of a 32°F freeze by this date
- Growing season (frost-free)114 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°F avg. coldest night
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This week in your yard
As of Oct 17, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
No soil station with a fresh reading within 62 miles.
4-inch depth
No soil station with a fresh reading within 62 miles.
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 99645 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
No soil reading near this ZIP. Typical extension timing for your region: spring mid-April to early May.
Fertilizer window
Lawn region: North (cool-season). Timing only; always follow the product label.
- Kentucky bluegrass (cool-season): Early fall: Around Labor Day (late August–September); Late fall: Late October–November, before the ground freezes; Late spring: Optional around Memorial Day. Avoid: Early-spring and midsummer feeding (pushes top growth, favors crabgrass).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | May 9 |
| 50% (the "average" last frost) | May 22 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 3 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Sep 1 |
| 50% (the "average" first frost) | Sep 16 |
| 90% (late: most years have frozen by now) | Sep 28 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Jun 7 | Sep 1 |
| 32°F (freeze) | May 22 | Sep 16 |
| 28°F (hard freeze) | May 6 | Sep 28 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 99645
Dates count from your average last spring frost (May 22) and first fall frost (Sep 16). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Mar 27–Apr 10 | May 29–Jun 12 (transplant) | – |
| Pepper (sweet and hot) | Mar 13–27 | Jun 5–19 (transplant) | – |
| Eggplant | Mar 13–27 | Jun 5–19 (transplant) | – |
| Tomatillo | Mar 27–Apr 10 | May 29–Jun 12 (transplant) | – |
| Lettuce | Mar 27–Apr 10 | May 1–22 (transplant) Apr 24–Jun 5 (sow outdoors) | Jul 22–Aug 12 (transplant) Jul 8–Aug 5 (sowing) |
| Spinach | – | Apr 10–May 1 (sow outdoors) | Jul 22–Aug 12 (sowing) |
| Kale | Mar 27–Apr 10 | Apr 24–May 8 (transplant) Apr 24–May 8 (sow outdoors) | Jun 24–Jul 22 (transplant) Jun 10–Jul 8 (sowing) |
| Collards | Mar 27–Apr 10 | Apr 24–May 22 (transplant) Apr 24–May 22 (sow outdoors) | Jun 24–Jul 22 (transplant) Jun 10–Jul 8 (sowing) |
| Broccoli | Mar 13–27 | Apr 24–May 8 (transplant) | Jun 10–Jul 8 (transplant) |
| Cabbage | Mar 13–27 | Apr 24–May 8 (transplant) | Jun 10–Jul 8 (transplant) |
| Cauliflower | Mar 13–27 | May 8–22 (transplant) | Jun 10–Jul 8 (transplant) |
| Brussels sprouts | Feb 27–Mar 13 | Apr 24–May 8 (transplant) | May 27–Jun 17 (transplant) |
| Kohlrabi | Mar 27–Apr 10 | Apr 24–May 8 (transplant) Apr 24–May 8 (sow outdoors) | Jul 8–22 (sowing) |
| Bok choy / Asian greens | – | Apr 24–May 8 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Arugula | – | Apr 24–May 22 (sow outdoors) | Jul 22–Aug 19 (sowing) |
| Mustard greens | – | Apr 24–May 15 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Swiss chard | Apr 10–24 | May 8–29 (transplant) May 8–Jun 5 (sow outdoors) | Jul 8–22 (sowing) |
| Beet | – | Apr 24–May 22 (sow outdoors) | Jul 8–22 (sowing) |
| Carrot | – | May 1–29 (sow outdoors) | Jun 24–Jul 8 (sowing) |
| Radish | – | Apr 17–May 29 (sow outdoors) | Aug 5–19 (sowing) |
| Turnip | – | Apr 24–May 15 (sow outdoors) | Jul 8–22 (sowing) |
| Parsnip | – | May 1–22 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 27–Apr 24 (sow outdoors) | Jun 24–Jul 8 (sowing) |
| Onion (bulbing) | Feb 27–Mar 13 | Apr 10–24 (transplant) | – |
| Green onion / scallion | – | Apr 10–May 8 (sow outdoors) | Jul 8–22 (sowing) |
| Leek | Feb 27–Mar 13 | Apr 24–May 8 (transplant) | – |
| Garlic | – | – | Aug 5–Sep 2 (sowing) |
| Shallot | – | Apr 10–24 (transplant) | Aug 5–Sep 2 (sowing) |
| Potato | – | Apr 24–May 8 (transplant) | May 27–Jun 10 (transplant) |
| Sweet potato | – | Jun 12–26 (transplant) | – |
| Sweet corn | – | May 29–Jun 12 (sow outdoors) | – |
| Bean, bush (snap) | – | May 29–Jun 12 (sow outdoors) | – |
| Bean, pole | – | May 29–Jun 12 (sow outdoors) | – |
| Lima bean | – | Jun 5–19 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 12–Jul 3 (sow outdoors) | – |
| Cucumber | Apr 24–May 1 | May 29–Jun 12 (transplant) May 29–Jun 12 (sow outdoors) | – |
| Summer squash / zucchini | Apr 24–May 1 | May 29–Jun 12 (transplant) May 29–Jun 12 (sow outdoors) | – |
| Winter squash | Apr 24–May 1 | May 29–Jun 12 (transplant) May 29–Jun 12 (sow outdoors) | – |
| Pumpkin | – | May 29–Jun 12 (sow outdoors) | – |
| Watermelon | Apr 24–May 1 | Jun 5–19 (transplant) Jun 5–19 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 24–May 1 | Jun 5–19 (transplant) Jun 5–19 (sow outdoors) | – |
| Okra | Apr 10–24 | Jun 5–19 (transplant) Jun 5–19 (sow outdoors) | – |
| Celery | Feb 27–Mar 13 | May 29–Jun 5 (transplant) | – |
| Basil | Apr 10–24 | May 29–Jun 12 (transplant) May 29–Jun 12 (sow outdoors) | – |
| Cilantro | – | May 8–Jun 5 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Parsley | Mar 13–27 | May 8–22 (transplant) May 1–22 (sow outdoors) | – |
| Dill | – | May 22–Jun 5 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Sunflower | – | May 22–Jun 5 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 24–May 8 (transplant) | – |
| Rhubarb (crowns) | – | Apr 24–May 8 (transplant) | – |
| Strawberry (plants) | – | Apr 24–May 8 (transplant) | Jul 8–Aug 5 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: Lazy Mtn, AK (NOAA GHCN-Daily ID USC00505464), elevation 733 ft, 1.8 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Palmer Muni AP, AK | 4 mi | May 6 | Sep 25 |
| Palmer Job Corps, AK | 5 mi | Apr 24 | Oct 4 |
| Sutton 1 W, AK | 7 mi | Jun 1 | Sep 6 |
The average last-frost dates of these stations span 39 days, a rough guide to local variation. See data sources & methods.
Frost questions for 99645
When is the last frost in 99645?
The average (50% chance) last spring freeze of 32°F for ZIP 99645 is May 22. For a more cautious planting date, use June 3, when only 1 year in 10 still sees a later freeze.
When is the first frost in 99645?
The average first fall freeze is September 16. In 1 year in 10 it comes by September 1.
What hardiness zone is 99645?
ZIP 99645 is in USDA zone 5a (-20 to -15°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 99645 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
99654 Tanaina 99567 Anchorage 99688 Willow 99694 Houston 99674 Glacier View 99505 Anchorage 99577 Anchorage 99623 Point MacKenzie
Other ZIP codes in Matanuska-Susitna Borough
99623 99652 99654 99667 99674 99676 99683 99688 99694 99729 All Matanuska-Susitna Borough frost dates · Alaska frost dates
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