Fall in zone 4bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59648 (Milford Colony, 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, Rogers Pass 9 NNE, MT (8 miles away).
- Average last spring frostMay 2150% chance of a 32°F freeze after this date
- Average first fall frostSep 1550% chance of a 32°F freeze by this date
- Growing season (frost-free)115 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
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 59648 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 7 |
| 50% (the "average" last frost) | May 21 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 8 |
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 30 |
| 50% (the "average" first frost) | Sep 15 |
| 90% (late: most years have frozen by now) | Sep 29 |
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) | May 21 | Sep 15 |
| 28°F (hard freeze) | May 7 | 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 59648
Dates count from your average last spring frost (May 21) and first fall frost (Sep 15). 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 26–Apr 9 | May 28–Jun 11 (transplant) | – |
| Pepper (sweet and hot) | Mar 12–26 | Jun 4–18 (transplant) | – |
| Eggplant | Mar 12–26 | Jun 4–18 (transplant) | – |
| Tomatillo | Mar 26–Apr 9 | May 28–Jun 11 (transplant) | – |
| Lettuce | Mar 26–Apr 9 | Apr 30–May 21 (transplant) Apr 23–Jun 4 (sow outdoors) | Jul 21–Aug 11 (transplant) Jul 7–Aug 4 (sowing) |
| Spinach | – | Apr 9–30 (sow outdoors) | Jul 21–Aug 11 (sowing) |
| Kale | Mar 26–Apr 9 | Apr 23–May 7 (transplant) Apr 23–May 7 (sow outdoors) | Jun 23–Jul 21 (transplant) Jun 9–Jul 7 (sowing) |
| Collards | Mar 26–Apr 9 | Apr 23–May 21 (transplant) Apr 23–May 21 (sow outdoors) | Jun 23–Jul 21 (transplant) Jun 9–Jul 7 (sowing) |
| Broccoli | Mar 12–26 | Apr 23–May 7 (transplant) | Jun 9–Jul 7 (transplant) |
| Cabbage | Mar 12–26 | Apr 23–May 7 (transplant) | Jun 9–Jul 7 (transplant) |
| Cauliflower | Mar 12–26 | May 7–21 (transplant) | Jun 9–Jul 7 (transplant) |
| Brussels sprouts | Feb 26–Mar 12 | Apr 23–May 7 (transplant) | May 26–Jun 16 (transplant) |
| Kohlrabi | Mar 26–Apr 9 | Apr 23–May 7 (transplant) Apr 23–May 7 (sow outdoors) | Jul 7–21 (sowing) |
| Bok choy / Asian greens | – | Apr 23–May 7 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Arugula | – | Apr 23–May 21 (sow outdoors) | Jul 21–Aug 18 (sowing) |
| Mustard greens | – | Apr 23–May 14 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Swiss chard | Apr 9–23 | May 7–28 (transplant) May 7–Jun 4 (sow outdoors) | Jul 7–21 (sowing) |
| Beet | – | Apr 23–May 21 (sow outdoors) | Jul 7–21 (sowing) |
| Carrot | – | Apr 30–May 28 (sow outdoors) | Jun 23–Jul 7 (sowing) |
| Radish | – | Apr 16–May 28 (sow outdoors) | Aug 4–18 (sowing) |
| Turnip | – | Apr 23–May 14 (sow outdoors) | Jul 7–21 (sowing) |
| Parsnip | – | Apr 30–May 21 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 26–Apr 23 (sow outdoors) | Jun 23–Jul 7 (sowing) |
| Onion (bulbing) | Feb 26–Mar 12 | Apr 9–23 (transplant) | – |
| Green onion / scallion | – | Apr 9–May 7 (sow outdoors) | Jul 7–21 (sowing) |
| Leek | Feb 26–Mar 12 | Apr 23–May 7 (transplant) | – |
| Garlic | – | – | Aug 4–Sep 1 (sowing) |
| Shallot | – | Apr 9–23 (transplant) | Aug 4–Sep 1 (sowing) |
| Potato | – | Apr 23–May 7 (transplant) | May 26–Jun 9 (transplant) |
| Sweet potato | – | Jun 11–25 (transplant) | – |
| Sweet corn | – | May 28–Jun 11 (sow outdoors) | – |
| Bean, bush (snap) | – | May 28–Jun 11 (sow outdoors) | – |
| Bean, pole | – | May 28–Jun 11 (sow outdoors) | – |
| Lima bean | – | Jun 4–18 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 11–Jul 2 (sow outdoors) | – |
| Cucumber | Apr 23–30 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Summer squash / zucchini | Apr 23–30 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Winter squash | Apr 23–30 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Pumpkin | – | May 28–Jun 11 (sow outdoors) | – |
| Watermelon | Apr 23–30 | Jun 4–18 (transplant) Jun 4–18 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 23–30 | Jun 4–18 (transplant) Jun 4–18 (sow outdoors) | – |
| Okra | Apr 9–23 | Jun 4–18 (transplant) Jun 4–18 (sow outdoors) | – |
| Celery | Feb 26–Mar 12 | May 28–Jun 4 (transplant) | – |
| Basil | Apr 9–23 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Cilantro | – | May 7–Jun 4 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Parsley | Mar 12–26 | May 7–21 (transplant) Apr 30–May 21 (sow outdoors) | – |
| Dill | – | May 21–Jun 4 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Sunflower | – | May 21–Jun 4 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 23–May 7 (transplant) | – |
| Rhubarb (crowns) | – | Apr 23–May 7 (transplant) | – |
| Strawberry (plants) | – | Apr 23–May 7 (transplant) | Jul 7–Aug 4 (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: Rogers Pass 9 NNE, MT (NOAA GHCN-Daily ID USC00247159), elevation 4,200 ft, 7.9 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Holter Dam, MT | 11 mi | May 19 | Sep 24 |
| Cascade 5 S, MT | 25 mi | May 21 | Sep 19 |
| Adel, MT | 26 mi | Jun 4 | Sep 12 |
The average last-frost dates of these stations span 16 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59648
When is the last frost in 59648?
The average (50% chance) last spring freeze of 32°F for ZIP 59648 is May 21. For a more cautious planting date, use June 8, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59648?
The average first fall freeze is September 15. In 1 year in 10 it comes by August 30.
What hardiness zone is 59648?
ZIP 59648 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 59648 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
59633 Canyon Creek 59640 Marysville 59421 Hardy 59477 Simms 59639 Lincoln 59602 Helena Valley Northeast 59636 Helena West Side 59483 Sun River
Other ZIP codes in Lewis and Clark County
59410 59601 59602 59623 59625 59633 59635 59636 59639 59640 All Lewis and Clark County frost dates · Montana frost dates
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- 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.