Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 82646 (Natrona County, WY)
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, Powder River #2, WY (12 miles away).
- Average last spring frostMay 2350% chance of a 32°F freeze after this date
- Average first fall frostSep 2050% chance of a 32°F freeze by this date
- Growing season (frost-free)121 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 18, 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 82646 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 mid-May.
Fertilizer window
Lawn region: Mountain West and High Plains. 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 23 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 5 |
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 7 |
| 50% (the "average" first frost) | Sep 20 |
| 90% (late: most years have frozen by now) | Oct 4 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Jun 5 | Sep 10 |
| 32°F (freeze) | May 23 | Sep 20 |
| 28°F (hard freeze) | May 10 | Oct 1 |
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 82646
Dates count from your average last spring frost (May 23) and first fall frost (Sep 20). 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 28–Apr 11 | May 30–Jun 13 (transplant) | – |
| Pepper (sweet and hot) | Mar 14–28 | Jun 6–20 (transplant) | – |
| Eggplant | Mar 14–28 | Jun 6–20 (transplant) | – |
| Tomatillo | Mar 28–Apr 11 | May 30–Jun 13 (transplant) | – |
| Lettuce | Mar 28–Apr 11 | May 2–23 (transplant) Apr 25–Jun 6 (sow outdoors) | Jul 26–Aug 16 (transplant) Jul 12–Aug 9 (sowing) |
| Spinach | – | Apr 11–May 2 (sow outdoors) | Jul 26–Aug 16 (sowing) |
| Kale | Mar 28–Apr 11 | Apr 25–May 9 (transplant) Apr 25–May 9 (sow outdoors) | Jun 28–Jul 26 (transplant) Jun 14–Jul 12 (sowing) |
| Collards | Mar 28–Apr 11 | Apr 25–May 23 (transplant) Apr 25–May 23 (sow outdoors) | Jun 28–Jul 26 (transplant) Jun 14–Jul 12 (sowing) |
| Broccoli | Mar 14–28 | Apr 25–May 9 (transplant) | Jun 14–Jul 12 (transplant) |
| Cabbage | Mar 14–28 | Apr 25–May 9 (transplant) | Jun 14–Jul 12 (transplant) |
| Cauliflower | Mar 14–28 | May 9–23 (transplant) | Jun 14–Jul 12 (transplant) |
| Brussels sprouts | Feb 28–Mar 14 | Apr 25–May 9 (transplant) | May 31–Jun 21 (transplant) |
| Kohlrabi | Mar 28–Apr 11 | Apr 25–May 9 (transplant) Apr 25–May 9 (sow outdoors) | Jul 12–26 (sowing) |
| Bok choy / Asian greens | – | Apr 25–May 9 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Arugula | – | Apr 25–May 23 (sow outdoors) | Jul 26–Aug 23 (sowing) |
| Mustard greens | – | Apr 25–May 16 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Swiss chard | Apr 11–25 | May 9–30 (transplant) May 9–Jun 6 (sow outdoors) | Jul 12–26 (sowing) |
| Beet | – | Apr 25–May 23 (sow outdoors) | Jul 12–26 (sowing) |
| Carrot | – | May 2–30 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Radish | – | Apr 18–May 30 (sow outdoors) | Aug 9–23 (sowing) |
| Turnip | – | Apr 25–May 16 (sow outdoors) | Jul 12–26 (sowing) |
| Parsnip | – | May 2–23 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 28–Apr 25 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Onion (bulbing) | Feb 28–Mar 14 | Apr 11–25 (transplant) | – |
| Green onion / scallion | – | Apr 11–May 9 (sow outdoors) | Jul 12–26 (sowing) |
| Leek | Feb 28–Mar 14 | Apr 25–May 9 (transplant) | – |
| Garlic | – | – | Aug 9–Sep 6 (sowing) |
| Shallot | – | Apr 11–25 (transplant) | Aug 9–Sep 6 (sowing) |
| Potato | – | Apr 25–May 9 (transplant) | May 31–Jun 14 (transplant) |
| Sweet potato | – | Jun 13–27 (transplant) | – |
| Sweet corn | – | May 30–Jun 13 (sow outdoors) | – |
| Bean, bush (snap) | – | May 30–Jun 13 (sow outdoors) | – |
| Bean, pole | – | May 30–Jun 13 (sow outdoors) | – |
| Lima bean | – | Jun 6–20 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 13–Jul 4 (sow outdoors) | – |
| Cucumber | Apr 25–May 2 | May 30–Jun 13 (transplant) May 30–Jun 13 (sow outdoors) | – |
| Summer squash / zucchini | Apr 25–May 2 | May 30–Jun 13 (transplant) May 30–Jun 13 (sow outdoors) | – |
| Winter squash | Apr 25–May 2 | May 30–Jun 13 (transplant) May 30–Jun 13 (sow outdoors) | – |
| Pumpkin | – | May 30–Jun 13 (sow outdoors) | – |
| Watermelon | Apr 25–May 2 | Jun 6–20 (transplant) Jun 6–20 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 25–May 2 | Jun 6–20 (transplant) Jun 6–20 (sow outdoors) | – |
| Okra | Apr 11–25 | Jun 6–20 (transplant) Jun 6–20 (sow outdoors) | – |
| Celery | Feb 28–Mar 14 | May 30–Jun 6 (transplant) | – |
| Basil | Apr 11–25 | May 30–Jun 13 (transplant) May 30–Jun 13 (sow outdoors) | – |
| Cilantro | – | May 9–Jun 6 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Parsley | Mar 14–28 | May 9–23 (transplant) May 2–23 (sow outdoors) | – |
| Dill | – | May 23–Jun 6 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Sunflower | – | May 23–Jun 6 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 25–May 9 (transplant) | – |
| Rhubarb (crowns) | – | Apr 25–May 9 (transplant) | – |
| Strawberry (plants) | – | Apr 25–May 9 (transplant) | Jul 12–Aug 9 (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: Powder River #2, WY (NOAA GHCN-Daily ID USC00487376), elevation 5,700 ft, 11.8 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Powder Rvr (school), WY | 12 mi | May 30 | Sep 22 |
| Casper Natrona Co AP, WY | 16 mi | May 26 | Sep 22 |
| Casper Wwtp, WY | 25 mi | May 10 | Sep 29 |
The average last-frost dates of these stations span 20 days, a rough guide to local variation. See data sources & methods.
Frost questions for 82646
When is the last frost in 82646?
The average (50% chance) last spring freeze of 32°F for ZIP 82646 is May 23. For a more cautious planting date, use June 5, when only 1 year in 10 still sees a later freeze.
When is the first frost in 82646?
The average first fall freeze is September 20. In 1 year in 10 it comes by September 7.
What hardiness zone is 82646?
ZIP 82646 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 82646 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
82604 Vista West 82648 Powder River 82644 Mills 82601 Casper Mountain 82638 82636 Evansville 82609 Casper 82620 Alcova
Other ZIP codes in Natrona County
82601 82604 82609 82620 82630 82635 82636 82638 82643 82644 82648 All Natrona County frost dates · Wyoming frost dates
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- Freeze alerts
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Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.