Fall in zone 5bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 83340 (Ketchum, 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, Fairfield Rs, ID (29 miles away).
Station is a bit far
The nearest station with freeze normals is over 40 km away, so dates here may be off by a week or more.
- Average last spring frostJun 850% chance of a 32°F freeze after this date
- Average first fall frostSep 1450% chance of a 32°F freeze by this date
- Growing season (frost-free)97 daysmedian, 32°F threshold
- USDA hardiness zone5b-15 to -10°F avg. coldest night
Get The Dial for 83340 (Ketchum)
Frost and freeze alerts from the NWS forecast for 83340, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
- Freeze alerts
- Soil-temp heads-up
- Weekly yard to-dos
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.
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
46°F Below 50°F
24-hour average · latest 47°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Arco 17 SW (55 mi).
4-inch depth
48°F Below 50°F
24-hour average · latest 50°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Arco 17 SW (55 mi).
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 83340 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 48°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent window is mostly past. Next: spring, when soil reaches 50°F (typically 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 15 |
| 50% (the "average" last frost) | Jun 8 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 28 |
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) | Aug 29 |
| 50% (the "average" first frost) | Sep 14 |
| 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) | n/a | n/a |
| 32°F (freeze) | Jun 8 | Sep 14 |
| 28°F (hard freeze) | May 11 | 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 83340
Dates count from your average last spring frost (Jun 8) and first fall frost (Sep 14). 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 | Apr 13–27 | Jun 15–29 (transplant) | – |
| Pepper (sweet and hot) | Mar 30–Apr 13 | Jun 22–Jul 6 (transplant) | – |
| Eggplant | Mar 30–Apr 13 | Jun 22–Jul 6 (transplant) | – |
| Tomatillo | Apr 13–27 | Jun 15–29 (transplant) | – |
| Lettuce | Apr 13–27 | May 18–Jun 8 (transplant) May 11–Jun 22 (sow outdoors) | Jul 20–Aug 10 (transplant) Jul 6–Aug 3 (sowing) |
| Spinach | – | Apr 27–May 18 (sow outdoors) | Jul 20–Aug 10 (sowing) |
| Kale | Apr 13–27 | May 11–25 (transplant) May 11–25 (sow outdoors) | Jun 22–Jul 20 (transplant) Jun 8–Jul 6 (sowing) |
| Collards | Apr 13–27 | May 11–Jun 8 (transplant) May 11–Jun 8 (sow outdoors) | Jun 22–Jul 20 (transplant) |
| Broccoli | Mar 30–Apr 13 | May 11–25 (transplant) | Jun 8–Jul 6 (transplant) |
| Cabbage | Mar 30–Apr 13 | May 11–25 (transplant) | Jun 8–Jul 6 (transplant) |
| Cauliflower | Mar 30–Apr 13 | May 25–Jun 8 (transplant) | – |
| Brussels sprouts | Mar 16–30 | May 11–25 (transplant) | – |
| Kohlrabi | Apr 13–27 | May 11–25 (transplant) May 11–25 (sow outdoors) | Jul 6–20 (sowing) |
| Bok choy / Asian greens | – | May 11–25 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Arugula | – | May 11–Jun 8 (sow outdoors) | Jul 20–Aug 17 (sowing) |
| Mustard greens | – | May 11–Jun 1 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Swiss chard | Apr 27–May 11 | May 25–Jun 15 (transplant) May 25–Jun 22 (sow outdoors) | Jul 6–20 (sowing) |
| Beet | – | May 11–Jun 8 (sow outdoors) | Jul 6–20 (sowing) |
| Carrot | – | May 18–Jun 15 (sow outdoors) | Jun 22–Jul 6 (sowing) |
| Radish | – | May 4–Jun 15 (sow outdoors) | Aug 3–17 (sowing) |
| Turnip | – | May 11–Jun 1 (sow outdoors) | Jul 6–20 (sowing) |
| Parsnip | – | May 18–Jun 8 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 13–May 11 (sow outdoors) | Jun 22–Jul 6 (sowing) |
| Onion (bulbing) | Mar 16–30 | Apr 27–May 11 (transplant) | – |
| Green onion / scallion | – | Apr 27–May 25 (sow outdoors) | Jul 6–20 (sowing) |
| Leek | Mar 16–30 | May 11–25 (transplant) | – |
| Garlic | – | – | Aug 3–31 (sowing) |
| Shallot | – | Apr 27–May 11 (transplant) | Aug 3–31 (sowing) |
| Potato | – | May 11–25 (transplant) | – |
| Sweet potato | – | Jun 29–Jul 13 (transplant) | – |
| Sweet corn | – | Jun 15–29 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 15–29 (sow outdoors) | – |
| Bean, pole | – | Jun 15–29 (sow outdoors) | – |
| Lima bean | – | Jun 22–Jul 6 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 29–Jul 20 (sow outdoors) | – |
| Cucumber | May 11–18 | Jun 15–29 (transplant) Jun 15–29 (sow outdoors) | – |
| Summer squash / zucchini | May 11–18 | Jun 15–29 (transplant) Jun 15–29 (sow outdoors) | – |
| Winter squash | May 11–18 | Jun 15–29 (transplant) Jun 15–29 (sow outdoors) | – |
| Pumpkin | – | Jun 15–29 (sow outdoors) | – |
| Watermelon | May 11–18 | Jun 22–Jul 6 (transplant) Jun 22–Jul 6 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 11–18 | Jun 22–Jul 6 (transplant) Jun 22–Jul 6 (sow outdoors) | – |
| Okra | Apr 27–May 11 | Jun 22–Jul 6 (transplant) Jun 22–Jul 6 (sow outdoors) | – |
| Celery | Mar 16–30 | Jun 15–22 (transplant) | – |
| Basil | Apr 27–May 11 | Jun 15–29 (transplant) Jun 15–29 (sow outdoors) | – |
| Cilantro | – | May 25–Jun 22 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Parsley | Mar 30–Apr 13 | May 25–Jun 8 (transplant) May 18–Jun 8 (sow outdoors) | – |
| Dill | – | Jun 8–22 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Sunflower | – | Jun 8–22 (sow outdoors) | – |
| Asparagus (crowns) | – | May 11–25 (transplant) | – |
| Rhubarb (crowns) | – | May 11–25 (transplant) | – |
| Strawberry (plants) | – | May 11–25 (transplant) | Jul 6–Aug 3 (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: Fairfield Rs, ID (NOAA GHCN-Daily ID USC00103108), elevation 5,065 ft, 29.1 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Bellevue, ID | 25 mi | May 13 | Oct 2 |
| Hill City 1 W, ID | 39 mi | Jun 16 | Sep 6 |
| Picabo, ID | 39 mi | Jun 16 | Sep 9 |
The average last-frost dates of these stations span 34 days, a rough guide to local variation. See data sources & methods.
Frost questions for 83340
When is the last frost in 83340?
The average (50% chance) last spring freeze of 32°F for ZIP 83340 is June 8. For a more cautious planting date, use June 28, when only 1 year in 10 still sees a later freeze.
When is the first frost in 83340?
The average first fall freeze is September 14. In 1 year in 10 it comes by August 29.
What hardiness zone is 83340?
ZIP 83340 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 83340 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
83353 Sun Valley 83354 Sun Valley 83327 Fairfield 83333 Hailey 83227 Clayton 83716 Robie Creek 83313 Gannett 83322
Other ZIP codes in Blaine County
83313 83320 83333 83348 83353 83354 All Blaine County frost dates · Idaho frost dates
Never miss a frost: get The Dial
Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
- Soil-temp heads-up
- Weekly yard to-dos
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.