Fall in zone 4bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59448 (Heart Butte, 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, E Glacier, MT (21 miles away).
- Average last spring frostJun 850% chance of a 32°F freeze after this date
- Average first fall frostSep 550% chance of a 32°F freeze by this date
- Growing season (frost-free)88 daysmedian, 32°F threshold
- USDA hardiness zone4b-25 to -20°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
46°F Below 50°F
24-hour average · latest 45°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Conrad Ag Rc (43 mi).
4-inch depth
46°F Below 50°F
24-hour average · latest 47°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Conrad Ag Rc (43 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 59448 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 24 |
| 50% (the "average" last frost) | Jun 8 |
| 10% (cautious: only 1 year in 10 freezes later) | Jul 1 |
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 20 |
| 50% (the "average" first frost) | Sep 5 |
| 90% (late: most years have frozen by now) | Sep 20 |
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 5 |
| 28°F (hard freeze) | May 21 | Sep 23 |
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 59448
Dates count from your average last spring frost (Jun 8) and first fall frost (Sep 5). 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 11–Aug 1 (transplant) Jun 27–Jul 25 (sowing) |
| Spinach | – | Apr 27–May 18 (sow outdoors) | Jul 11–Aug 1 (sowing) |
| Kale | Apr 13–27 | May 11–25 (transplant) May 11–25 (sow outdoors) | Jun 13–Jul 11 (transplant) May 30–Jun 27 (sowing) |
| Collards | Apr 13–27 | May 11–Jun 8 (transplant) May 11–Jun 8 (sow outdoors) | Jun 13–Jul 11 (transplant) |
| Broccoli | Mar 30–Apr 13 | May 11–25 (transplant) | May 30–Jun 27 (transplant) |
| Cabbage | Mar 30–Apr 13 | May 11–25 (transplant) | May 30–Jun 27 (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) | Jun 27–Jul 11 (sowing) |
| Bok choy / Asian greens | – | May 11–25 (sow outdoors) | Jul 11–25 (sowing) |
| Arugula | – | May 11–Jun 8 (sow outdoors) | Jul 11–Aug 8 (sowing) |
| Mustard greens | – | May 11–Jun 1 (sow outdoors) | Jul 11–25 (sowing) |
| Swiss chard | Apr 27–May 11 | May 25–Jun 15 (transplant) May 25–Jun 22 (sow outdoors) | Jun 27–Jul 11 (sowing) |
| Beet | – | May 11–Jun 8 (sow outdoors) | Jun 27–Jul 11 (sowing) |
| Carrot | – | May 18–Jun 15 (sow outdoors) | – |
| Radish | – | May 4–Jun 15 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Turnip | – | May 11–Jun 1 (sow outdoors) | Jun 27–Jul 11 (sowing) |
| Parsnip | – | May 18–Jun 8 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 13–May 11 (sow outdoors) | Jun 13–27 (sowing) |
| Onion (bulbing) | Mar 16–30 | Apr 27–May 11 (transplant) | – |
| Green onion / scallion | – | Apr 27–May 25 (sow outdoors) | Jun 27–Jul 11 (sowing) |
| Leek | Mar 16–30 | May 11–25 (transplant) | – |
| Garlic | – | – | Jul 25–Aug 22 (sowing) |
| Shallot | – | Apr 27–May 11 (transplant) | Jul 25–Aug 22 (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 11–25 (sowing) |
| Parsley | Mar 30–Apr 13 | May 25–Jun 8 (transplant) May 18–Jun 8 (sow outdoors) | – |
| Dill | – | Jun 8–22 (sow outdoors) | Jul 11–25 (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) | Jun 27–Jul 25 (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: E Glacier, MT (NOAA GHCN-Daily ID USC00242629), elevation 4,806 ft, 21.4 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Blackleaf, MT | 26 mi | Jun 9 | Sep 3 |
| Valier, MT | 28 mi | May 17 | Sep 24 |
| Cut Bank Muni AP, MT | 32 mi | May 24 | Sep 15 |
The average last-frost dates of these stations span 23 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59448
When is the last frost in 59448?
The average (50% chance) last spring freeze of 32°F for ZIP 59448 is June 8. For a more cautious planting date, use July 1, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59448?
The average first fall freeze is September 5. In 1 year in 10 it comes by August 20.
What hardiness zone is 59448?
ZIP 59448 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 59448 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
59432 Dupuyer 59417 Starr School 59486 Valier 59467 Rockport Colony 59936 West Glacier 59419 Bynum 59422 New Rockport Colony 59427 Santa Rita
Other ZIP codes in Pondera County
59416 59425 59432 59486 All Pondera 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.