Fall in zone 4bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59318 (Garfield County, MT)
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, Jordan AP, MT (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 frostMay 1850% 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)123 daysmedian, 32°F threshold
- USDA hardiness zone4b-25 to -20°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 59318, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
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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
45°F Below 50°F
24-hour average · latest 45°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Jordan (18 mi).
4-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 Jordan (18 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 59318 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 46°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 6 |
| 50% (the "average" last frost) | May 18 |
| 10% (cautious: only 1 year in 10 freezes later) | May 31 |
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 8 |
| 50% (the "average" first frost) | Sep 20 |
| 90% (late: most years have frozen by now) | Oct 1 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 29 | Sep 11 |
| 32°F (freeze) | May 18 | Sep 20 |
| 28°F (hard freeze) | May 8 | Sep 29 |
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 59318
Dates count from your average last spring frost (May 18) 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 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) | Jul 26–Aug 16 (transplant) Jul 12–Aug 9 (sowing) |
| Spinach | – | Apr 6–27 (sow outdoors) | Jul 26–Aug 16 (sowing) |
| Kale | Mar 23–Apr 6 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | Jun 28–Jul 26 (transplant) Jun 14–Jul 12 (sowing) |
| Collards | Mar 23–Apr 6 | Apr 20–May 18 (transplant) Apr 20–May 18 (sow outdoors) | Jun 28–Jul 26 (transplant) Jun 14–Jul 12 (sowing) |
| Broccoli | Mar 9–23 | Apr 20–May 4 (transplant) | Jun 14–Jul 12 (transplant) |
| Cabbage | Mar 9–23 | Apr 20–May 4 (transplant) | Jun 14–Jul 12 (transplant) |
| Cauliflower | Mar 9–23 | May 4–18 (transplant) | Jun 14–Jul 12 (transplant) |
| Brussels sprouts | Feb 23–Mar 9 | Apr 20–May 4 (transplant) | May 31–Jun 21 (transplant) |
| Kohlrabi | Mar 23–Apr 6 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | Jul 12–26 (sowing) |
| Bok choy / Asian greens | – | Apr 20–May 4 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Arugula | – | Apr 20–May 18 (sow outdoors) | Jul 26–Aug 23 (sowing) |
| Mustard greens | – | Apr 20–May 11 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Swiss chard | Apr 6–20 | May 4–25 (transplant) May 4–Jun 1 (sow outdoors) | Jul 12–26 (sowing) |
| Beet | – | Apr 20–May 18 (sow outdoors) | Jul 12–26 (sowing) |
| Carrot | – | Apr 27–May 25 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Radish | – | Apr 13–May 25 (sow outdoors) | Aug 9–23 (sowing) |
| Turnip | – | Apr 20–May 11 (sow outdoors) | Jul 12–26 (sowing) |
| Parsnip | – | Apr 27–May 18 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 23–Apr 20 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Onion (bulbing) | Feb 23–Mar 9 | Apr 6–20 (transplant) | – |
| Green onion / scallion | – | Apr 6–May 4 (sow outdoors) | Jul 12–26 (sowing) |
| Leek | Feb 23–Mar 9 | Apr 20–May 4 (transplant) | – |
| Garlic | – | – | Aug 9–Sep 6 (sowing) |
| Shallot | – | Apr 6–20 (transplant) | Aug 9–Sep 6 (sowing) |
| Potato | – | Apr 20–May 4 (transplant) | May 31–Jun 14 (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) | Jul 26–Aug 9 (sowing) |
| Parsley | Mar 9–23 | May 4–18 (transplant) Apr 27–May 18 (sow outdoors) | – |
| Dill | – | May 18–Jun 1 (sow outdoors) | Jul 26–Aug 9 (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 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: Jordan AP, MT (NOAA GHCN-Daily ID USW00094051), elevation 2,662 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%) |
|---|---|---|---|
| Jordan, MT | 31 mi | May 21 | Sep 18 |
| Malta 35 S, MT | 31 mi | May 16 | Sep 23 |
| Mosby 4 ENE, MT | 36 mi | May 5 | Oct 4 |
The average last-frost dates of these stations span 16 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59318
When is the last frost in 59318?
The average (50% chance) last spring freeze of 32°F for ZIP 59318 is May 18. For a more cautious planting date, use May 31, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59318?
The average first fall freeze is September 20. In 1 year in 10 it comes by September 8.
What hardiness zone is 59318?
ZIP 59318 is in USDA zone 4b (-25 to -20°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 59318 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
59077 59337 Jordan 59058 59538 Malta 59087 Winnett 59322 59230 St. Marie 59546 Zortman
Other ZIP codes in Garfield County
59058 59077 59312 59322 59337 All Garfield County frost dates · Montana frost dates
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Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- 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.