Fall in zone 3bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59250 (Opheim, 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, Opheim 10 N, MT (15 miles away).
- Average last spring frostJun 150% chance of a 32°F freeze after this date
- Average first fall frostSep 750% chance of a 32°F freeze by this date
- Growing season (frost-free)99 daysmedian, 32°F threshold
- USDA hardiness zone3b-35 to -30°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 59250 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 20 |
| 50% (the "average" last frost) | Jun 1 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 18 |
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 24 |
| 50% (the "average" first frost) | Sep 7 |
| 90% (late: most years have frozen by now) | Sep 21 |
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 1 | Sep 7 |
| 28°F (hard freeze) | May 21 | Sep 19 |
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 59250
Dates count from your average last spring frost (Jun 1) and first fall frost (Sep 7). 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 6–20 | Jun 8–22 (transplant) | – |
| Pepper (sweet and hot) | Mar 23–Apr 6 | Jun 15–29 (transplant) | – |
| Eggplant | Mar 23–Apr 6 | Jun 15–29 (transplant) | – |
| Tomatillo | Apr 6–20 | Jun 8–22 (transplant) | – |
| Lettuce | Apr 6–20 | May 11–Jun 1 (transplant) May 4–Jun 15 (sow outdoors) | Jul 13–Aug 3 (transplant) Jun 29–Jul 27 (sowing) |
| Spinach | – | Apr 20–May 11 (sow outdoors) | Jul 13–Aug 3 (sowing) |
| Kale | Apr 6–20 | May 4–18 (transplant) May 4–18 (sow outdoors) | Jun 15–Jul 13 (transplant) Jun 1–29 (sowing) |
| Collards | Apr 6–20 | May 4–Jun 1 (transplant) May 4–Jun 1 (sow outdoors) | Jun 15–Jul 13 (transplant) |
| Broccoli | Mar 23–Apr 6 | May 4–18 (transplant) | Jun 1–29 (transplant) |
| Cabbage | Mar 23–Apr 6 | May 4–18 (transplant) | Jun 1–29 (transplant) |
| Cauliflower | Mar 23–Apr 6 | May 18–Jun 1 (transplant) | – |
| Brussels sprouts | Mar 9–23 | May 4–18 (transplant) | – |
| Kohlrabi | Apr 6–20 | May 4–18 (transplant) May 4–18 (sow outdoors) | Jun 29–Jul 13 (sowing) |
| Bok choy / Asian greens | – | May 4–18 (sow outdoors) | Jul 13–27 (sowing) |
| Arugula | – | May 4–Jun 1 (sow outdoors) | Jul 13–Aug 10 (sowing) |
| Mustard greens | – | May 4–25 (sow outdoors) | Jul 13–27 (sowing) |
| Swiss chard | Apr 20–May 4 | May 18–Jun 8 (transplant) May 18–Jun 15 (sow outdoors) | Jun 29–Jul 13 (sowing) |
| Beet | – | May 4–Jun 1 (sow outdoors) | Jun 29–Jul 13 (sowing) |
| Carrot | – | May 11–Jun 8 (sow outdoors) | Jun 15–29 (sowing) |
| Radish | – | Apr 27–Jun 8 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Turnip | – | May 4–25 (sow outdoors) | Jun 29–Jul 13 (sowing) |
| Parsnip | – | May 11–Jun 1 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 6–May 4 (sow outdoors) | Jun 15–29 (sowing) |
| Onion (bulbing) | Mar 9–23 | Apr 20–May 4 (transplant) | – |
| Green onion / scallion | – | Apr 20–May 18 (sow outdoors) | Jun 29–Jul 13 (sowing) |
| Leek | Mar 9–23 | May 4–18 (transplant) | – |
| Garlic | – | – | Jul 27–Aug 24 (sowing) |
| Shallot | – | Apr 20–May 4 (transplant) | Jul 27–Aug 24 (sowing) |
| Potato | – | May 4–18 (transplant) | – |
| Sweet potato | – | Jun 22–Jul 6 (transplant) | – |
| Sweet corn | – | Jun 8–22 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 8–22 (sow outdoors) | – |
| Bean, pole | – | Jun 8–22 (sow outdoors) | – |
| Lima bean | – | Jun 15–29 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 22–Jul 13 (sow outdoors) | – |
| Cucumber | May 4–11 | Jun 8–22 (transplant) Jun 8–22 (sow outdoors) | – |
| Summer squash / zucchini | May 4–11 | Jun 8–22 (transplant) Jun 8–22 (sow outdoors) | – |
| Winter squash | May 4–11 | Jun 8–22 (transplant) Jun 8–22 (sow outdoors) | – |
| Pumpkin | – | Jun 8–22 (sow outdoors) | – |
| Watermelon | May 4–11 | Jun 15–29 (transplant) Jun 15–29 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 4–11 | Jun 15–29 (transplant) Jun 15–29 (sow outdoors) | – |
| Okra | Apr 20–May 4 | Jun 15–29 (transplant) Jun 15–29 (sow outdoors) | – |
| Celery | Mar 9–23 | Jun 8–15 (transplant) | – |
| Basil | Apr 20–May 4 | Jun 8–22 (transplant) Jun 8–22 (sow outdoors) | – |
| Cilantro | – | May 18–Jun 15 (sow outdoors) | Jul 13–27 (sowing) |
| Parsley | Mar 23–Apr 6 | May 18–Jun 1 (transplant) May 11–Jun 1 (sow outdoors) | – |
| Dill | – | Jun 1–15 (sow outdoors) | Jul 13–27 (sowing) |
| Sunflower | – | Jun 1–15 (sow outdoors) | – |
| Asparagus (crowns) | – | May 4–18 (transplant) | – |
| Rhubarb (crowns) | – | May 4–18 (transplant) | – |
| Strawberry (plants) | – | May 4–18 (transplant) | Jun 29–Jul 27 (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: Opheim 10 N, MT (NOAA GHCN-Daily ID USC00246236), elevation 2,878 ft, 15.3 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Opheim 12 SSE, MT | 17 mi | Jun 5 | Sep 2 |
| St Marie, MT | 31 mi | May 13 | Sep 27 |
| Hinsdale 4 SW, MT | 42 mi | May 15 | Sep 26 |
The average last-frost dates of these stations span 23 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59250
When is the last frost in 59250?
The average (50% chance) last spring freeze of 32°F for ZIP 59250 is June 1. For a more cautious planting date, use June 18, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59250?
The average first fall freeze is September 7. In 1 year in 10 it comes by August 24.
What hardiness zone is 59250?
ZIP 59250 is in USDA zone 3b (-35 to -30°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 59250 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
59240 59244 59260 59231 St. Marie 59241 Hinsdale 59253 Peerless 59273 59261 Saco
Other ZIP codes in Valley County
59225 59230 59231 59240 59241 59244 59248 59260 59273 All Valley 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.