Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59871 (Sula, 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, Darby, MT (20 miles away).
- Average last spring frostMay 2450% chance of a 32°F freeze after this date
- Average first fall frostSep 2350% chance of a 32°F freeze by this date
- Growing season (frost-free)118 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 59871, 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
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 59871 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 6 |
| 50% (the "average" last frost) | May 24 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 14 |
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 4 |
| 50% (the "average" first frost) | Sep 23 |
| 90% (late: most years have frozen by now) | Oct 8 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Jun 16 | Sep 6 |
| 32°F (freeze) | May 24 | Sep 23 |
| 28°F (hard freeze) | May 5 | Oct 4 |
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 59871
Dates count from your average last spring frost (May 24) and first fall frost (Sep 23). 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 29–Apr 12 | May 31–Jun 14 (transplant) | – |
| Pepper (sweet and hot) | Mar 15–29 | Jun 7–21 (transplant) | – |
| Eggplant | Mar 15–29 | Jun 7–21 (transplant) | – |
| Tomatillo | Mar 29–Apr 12 | May 31–Jun 14 (transplant) | – |
| Lettuce | Mar 29–Apr 12 | May 3–24 (transplant) Apr 26–Jun 7 (sow outdoors) | Jul 29–Aug 19 (transplant) Jul 15–Aug 12 (sowing) |
| Spinach | – | Apr 12–May 3 (sow outdoors) | Jul 29–Aug 19 (sowing) |
| Kale | Mar 29–Apr 12 | Apr 26–May 10 (transplant) Apr 26–May 10 (sow outdoors) | Jul 1–29 (transplant) Jun 17–Jul 15 (sowing) |
| Collards | Mar 29–Apr 12 | Apr 26–May 24 (transplant) Apr 26–May 24 (sow outdoors) | Jul 1–29 (transplant) Jun 17–Jul 15 (sowing) |
| Broccoli | Mar 15–29 | Apr 26–May 10 (transplant) | Jun 17–Jul 15 (transplant) |
| Cabbage | Mar 15–29 | Apr 26–May 10 (transplant) | Jun 17–Jul 15 (transplant) |
| Cauliflower | Mar 15–29 | May 10–24 (transplant) | Jun 17–Jul 15 (transplant) |
| Brussels sprouts | Mar 1–15 | Apr 26–May 10 (transplant) | Jun 3–24 (transplant) |
| Kohlrabi | Mar 29–Apr 12 | Apr 26–May 10 (transplant) Apr 26–May 10 (sow outdoors) | Jul 15–29 (sowing) |
| Bok choy / Asian greens | – | Apr 26–May 10 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Arugula | – | Apr 26–May 24 (sow outdoors) | Jul 29–Aug 26 (sowing) |
| Mustard greens | – | Apr 26–May 17 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Swiss chard | Apr 12–26 | May 10–31 (transplant) May 10–Jun 7 (sow outdoors) | Jul 15–29 (sowing) |
| Beet | – | Apr 26–May 24 (sow outdoors) | Jul 15–29 (sowing) |
| Carrot | – | May 3–31 (sow outdoors) | Jul 1–15 (sowing) |
| Radish | – | Apr 19–May 31 (sow outdoors) | Aug 12–26 (sowing) |
| Turnip | – | Apr 26–May 17 (sow outdoors) | Jul 15–29 (sowing) |
| Parsnip | – | May 3–24 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 29–Apr 26 (sow outdoors) | Jul 1–15 (sowing) |
| Onion (bulbing) | Mar 1–15 | Apr 12–26 (transplant) | – |
| Green onion / scallion | – | Apr 12–May 10 (sow outdoors) | Jul 15–29 (sowing) |
| Leek | Mar 1–15 | Apr 26–May 10 (transplant) | – |
| Garlic | – | – | Aug 12–Sep 9 (sowing) |
| Shallot | – | Apr 12–26 (transplant) | Aug 12–Sep 9 (sowing) |
| Potato | – | Apr 26–May 10 (transplant) | Jun 3–17 (transplant) |
| Sweet potato | – | Jun 14–28 (transplant) | – |
| Sweet corn | – | May 31–Jun 14 (sow outdoors) | – |
| Bean, bush (snap) | – | May 31–Jun 14 (sow outdoors) | – |
| Bean, pole | – | May 31–Jun 14 (sow outdoors) | – |
| Lima bean | – | Jun 7–21 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 14–Jul 5 (sow outdoors) | – |
| Cucumber | Apr 26–May 3 | May 31–Jun 14 (transplant) May 31–Jun 14 (sow outdoors) | – |
| Summer squash / zucchini | Apr 26–May 3 | May 31–Jun 14 (transplant) May 31–Jun 14 (sow outdoors) | – |
| Winter squash | Apr 26–May 3 | May 31–Jun 14 (transplant) May 31–Jun 14 (sow outdoors) | – |
| Pumpkin | – | May 31–Jun 14 (sow outdoors) | – |
| Watermelon | Apr 26–May 3 | Jun 7–21 (transplant) Jun 7–21 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 26–May 3 | Jun 7–21 (transplant) Jun 7–21 (sow outdoors) | – |
| Okra | Apr 12–26 | Jun 7–21 (transplant) Jun 7–21 (sow outdoors) | – |
| Celery | Mar 1–15 | May 31–Jun 7 (transplant) | – |
| Basil | Apr 12–26 | May 31–Jun 14 (transplant) May 31–Jun 14 (sow outdoors) | – |
| Cilantro | – | May 10–Jun 7 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Parsley | Mar 15–29 | May 10–24 (transplant) May 3–24 (sow outdoors) | – |
| Dill | – | May 24–Jun 7 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Sunflower | – | May 24–Jun 7 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 26–May 10 (transplant) | – |
| Rhubarb (crowns) | – | Apr 26–May 10 (transplant) | – |
| Strawberry (plants) | – | Apr 26–May 10 (transplant) | Jul 15–Aug 12 (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: Darby, MT (NOAA GHCN-Daily ID USC00242221), elevation 3,880 ft, 19.6 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Gibbonsville #2, ID | 24 mi | Jun 1 | Sep 17 |
| Hamilton, MT | 30 mi | May 21 | Sep 22 |
| Western AG Rsch Ctr, MT | 33 mi | May 23 | Sep 21 |
The average last-frost dates of these stations span 11 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59871
When is the last frost in 59871?
The average (50% chance) last spring freeze of 32°F for ZIP 59871 is May 24. For a more cautious planting date, use June 14, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59871?
The average first fall freeze is September 23. In 1 year in 10 it comes by September 4.
What hardiness zone is 59871?
ZIP 59871 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 59871 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
59827 Conner 59829 Darby 59840 Hamilton 59762 Anaconda-Deer Lodge County 83463 59761 Wisdom 59828 Corvallis 59858 Philipsburg
Other ZIP codes in Ravalli County
59827 59828 59829 59833 59840 59841 59870 59875 All Ravalli 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.