Fall in zone 5bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 83446 (Spencer, ID)
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, Dubois EXP STN, ID (8 miles away).
- Average last spring frostMay 1850% chance of a 32°F freeze after this date
- Average first fall frostSep 3050% chance of a 32°F freeze by this date
- Growing season (frost-free)132 daysmedian, 32°F threshold
- USDA hardiness zone5b-15 to -10°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 83446 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 3 |
| 50% (the "average" last frost) | May 18 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 9 |
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 14 |
| 50% (the "average" first frost) | Sep 30 |
| 90% (late: most years have frozen by now) | Oct 16 |
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 18 |
| 32°F (freeze) | May 18 | Sep 30 |
| 28°F (hard freeze) | May 2 | Oct 12 |
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 83446
Dates count from your average last spring frost (May 18) and first fall frost (Sep 30). 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 23–Apr 6 | May 25–Jun 8 (transplant) | – |
| Pepper (sweet and hot) | Mar 9–23 | Jun 1–15 (transplant) | – |
| Eggplant | Mar 9–23 | Jun 1–15 (transplant) | – |
| Tomatillo | Mar 23–Apr 6 | May 25–Jun 8 (transplant) | – |
| Lettuce | Mar 23–Apr 6 | Apr 27–May 18 (transplant) Apr 20–Jun 1 (sow outdoors) | Aug 5–26 (transplant) Jul 22–Aug 19 (sowing) |
| Spinach | – | Apr 6–27 (sow outdoors) | Aug 5–26 (sowing) |
| Kale | Mar 23–Apr 6 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | Jul 8–Aug 5 (transplant) Jun 24–Jul 22 (sowing) |
| Collards | Mar 23–Apr 6 | Apr 20–May 18 (transplant) Apr 20–May 18 (sow outdoors) | Jul 8–Aug 5 (transplant) Jun 24–Jul 22 (sowing) |
| Broccoli | Mar 9–23 | Apr 20–May 4 (transplant) | Jun 24–Jul 22 (transplant) |
| Cabbage | Mar 9–23 | Apr 20–May 4 (transplant) | Jun 24–Jul 22 (transplant) |
| Cauliflower | Mar 9–23 | May 4–18 (transplant) | Jun 24–Jul 22 (transplant) |
| Brussels sprouts | Feb 23–Mar 9 | Apr 20–May 4 (transplant) | Jun 10–Jul 1 (transplant) |
| Kohlrabi | Mar 23–Apr 6 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Bok choy / Asian greens | – | Apr 20–May 4 (sow outdoors) | Aug 5–19 (sowing) |
| Arugula | – | Apr 20–May 18 (sow outdoors) | Aug 5–Sep 2 (sowing) |
| Mustard greens | – | Apr 20–May 11 (sow outdoors) | Aug 5–19 (sowing) |
| Swiss chard | Apr 6–20 | May 4–25 (transplant) May 4–Jun 1 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Beet | – | Apr 20–May 18 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Carrot | – | Apr 27–May 25 (sow outdoors) | Jul 8–22 (sowing) |
| Radish | – | Apr 13–May 25 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Turnip | – | Apr 20–May 11 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Parsnip | – | Apr 27–May 18 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 23–Apr 20 (sow outdoors) | Jul 8–22 (sowing) |
| Onion (bulbing) | Feb 23–Mar 9 | Apr 6–20 (transplant) | – |
| Green onion / scallion | – | Apr 6–May 4 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Leek | Feb 23–Mar 9 | Apr 20–May 4 (transplant) | – |
| Garlic | – | – | Aug 19–Sep 16 (sowing) |
| Shallot | – | Apr 6–20 (transplant) | Aug 19–Sep 16 (sowing) |
| Potato | – | Apr 20–May 4 (transplant) | Jun 10–24 (transplant) |
| Sweet potato | – | Jun 8–22 (transplant) | – |
| Sweet corn | – | May 25–Jun 8 (sow outdoors) | – |
| Bean, bush (snap) | – | May 25–Jun 8 (sow outdoors) | – |
| Bean, pole | – | May 25–Jun 8 (sow outdoors) | – |
| Lima bean | – | Jun 1–15 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 8–29 (sow outdoors) | – |
| Cucumber | Apr 20–27 | May 25–Jun 8 (transplant) May 25–Jun 8 (sow outdoors) | – |
| Summer squash / zucchini | Apr 20–27 | May 25–Jun 8 (transplant) May 25–Jun 8 (sow outdoors) | – |
| Winter squash | Apr 20–27 | May 25–Jun 8 (transplant) May 25–Jun 8 (sow outdoors) | – |
| Pumpkin | – | May 25–Jun 8 (sow outdoors) | – |
| Watermelon | Apr 20–27 | Jun 1–15 (transplant) Jun 1–15 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 20–27 | Jun 1–15 (transplant) Jun 1–15 (sow outdoors) | – |
| Okra | Apr 6–20 | Jun 1–15 (transplant) Jun 1–15 (sow outdoors) | – |
| Celery | Feb 23–Mar 9 | May 25–Jun 1 (transplant) | – |
| Basil | Apr 6–20 | May 25–Jun 8 (transplant) May 25–Jun 8 (sow outdoors) | – |
| Cilantro | – | May 4–Jun 1 (sow outdoors) | Aug 5–19 (sowing) |
| Parsley | Mar 9–23 | May 4–18 (transplant) Apr 27–May 18 (sow outdoors) | – |
| Dill | – | May 18–Jun 1 (sow outdoors) | Aug 5–19 (sowing) |
| Sunflower | – | May 18–Jun 1 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 20–May 4 (transplant) | – |
| Rhubarb (crowns) | – | Apr 20–May 4 (transplant) | – |
| Strawberry (plants) | – | Apr 20–May 4 (transplant) | Jul 22–Aug 19 (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: Dubois EXP STN, ID (NOAA GHCN-Daily ID USC00102707), elevation 5,450 ft, 8.5 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Small 6N, ID | 11 mi | Jun 5 | Sep 20 |
| Lima, MT | 26 mi | Jun 11 | Sep 10 |
| Hamer 4 NW, ID | 28 mi | Jun 3 | Sep 11 |
The average last-frost dates of these stations span 24 days, a rough guide to local variation. See data sources & methods.
Frost questions for 83446
When is the last frost in 83446?
The average (50% chance) last spring freeze of 32°F for ZIP 83446 is May 18. For a more cautious planting date, use June 9, when only 1 year in 10 still sees a later freeze.
When is the first frost in 83446?
The average first fall freeze is September 30. In 1 year in 10 it comes by September 14.
What hardiness zone is 83446?
ZIP 83446 is in USDA zone 5b (-15 to -10°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 83446 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
83423 Dubois 59739 Lakeview 83425 Hamer 83445 St. Anthony 83435 59724 Dell 83438 Parker 83450 Mud Lake
Other ZIP codes in Clark County
83423 All Clark County frost dates · Idaho frost dates
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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.