Fall in zone 3bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59501 (Herron, 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, Havre City Co AP, MT (10 miles away).
- Average last spring frostMay 1550% 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)129 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
49°F Below 50°F
24-hour average · latest 48°F, as of Oct 18, 2:00 AM CDT
Measured at USDA NRCS SCAN station Fort Assiniboine #1, 14 mi away. Daily averages: Thu 46°, Fri 45°, Sat 49°.
4-inch depth
47°F Below 50°F
24-hour average · latest 48°F, as of Oct 18, 2:00 AM CDT
Measured at USDA NRCS SCAN station Fort Assiniboine #1, 14 mi away. Daily averages: Thu 45°, Fri 44°, Sat 47°.
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 59501 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 47°F at 4 inches. 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 3 |
| 50% (the "average" last frost) | May 15 |
| 10% (cautious: only 1 year in 10 freezes later) | May 27 |
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 11 |
| 50% (the "average" first frost) | Sep 23 |
| 90% (late: most years have frozen by now) | Oct 5 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 27 | Sep 12 |
| 32°F (freeze) | May 15 | Sep 23 |
| 28°F (hard freeze) | May 3 | Oct 1 |
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 59501
Dates count from your average last spring frost (May 15) 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 20–Apr 3 | May 22–Jun 5 (transplant) | – |
| Pepper (sweet and hot) | Mar 6–20 | May 29–Jun 12 (transplant) | – |
| Eggplant | Mar 6–20 | May 29–Jun 12 (transplant) | – |
| Tomatillo | Mar 20–Apr 3 | May 22–Jun 5 (transplant) | – |
| Lettuce | Mar 20–Apr 3 | Apr 24–May 15 (transplant) Apr 17–May 29 (sow outdoors) | Jul 29–Aug 19 (transplant) Jul 15–Aug 12 (sowing) |
| Spinach | – | Apr 3–24 (sow outdoors) | Jul 29–Aug 19 (sowing) |
| Kale | Mar 20–Apr 3 | Apr 17–May 1 (transplant) Apr 17–May 1 (sow outdoors) | Jul 1–29 (transplant) Jun 17–Jul 15 (sowing) |
| Collards | Mar 20–Apr 3 | Apr 17–May 15 (transplant) Apr 17–May 15 (sow outdoors) | Jul 1–29 (transplant) Jun 17–Jul 15 (sowing) |
| Broccoli | Mar 6–20 | Apr 17–May 1 (transplant) | Jun 17–Jul 15 (transplant) |
| Cabbage | Mar 6–20 | Apr 17–May 1 (transplant) | Jun 17–Jul 15 (transplant) |
| Cauliflower | Mar 6–20 | May 1–15 (transplant) | Jun 17–Jul 15 (transplant) |
| Brussels sprouts | Feb 20–Mar 6 | Apr 17–May 1 (transplant) | Jun 3–24 (transplant) |
| Kohlrabi | Mar 20–Apr 3 | Apr 17–May 1 (transplant) Apr 17–May 1 (sow outdoors) | Jul 15–29 (sowing) |
| Bok choy / Asian greens | – | Apr 17–May 1 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Arugula | – | Apr 17–May 15 (sow outdoors) | Jul 29–Aug 26 (sowing) |
| Mustard greens | – | Apr 17–May 8 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Swiss chard | Apr 3–17 | May 1–22 (transplant) May 1–29 (sow outdoors) | Jul 15–29 (sowing) |
| Beet | – | Apr 17–May 15 (sow outdoors) | Jul 15–29 (sowing) |
| Carrot | – | Apr 24–May 22 (sow outdoors) | Jul 1–15 (sowing) |
| Radish | – | Apr 10–May 22 (sow outdoors) | Aug 12–26 (sowing) |
| Turnip | – | Apr 17–May 8 (sow outdoors) | Jul 15–29 (sowing) |
| Parsnip | – | Apr 24–May 15 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 20–Apr 17 (sow outdoors) | Jul 1–15 (sowing) |
| Onion (bulbing) | Feb 20–Mar 6 | Apr 3–17 (transplant) | – |
| Green onion / scallion | – | Apr 3–May 1 (sow outdoors) | Jul 15–29 (sowing) |
| Leek | Feb 20–Mar 6 | Apr 17–May 1 (transplant) | – |
| Garlic | – | – | Aug 12–Sep 9 (sowing) |
| Shallot | – | Apr 3–17 (transplant) | Aug 12–Sep 9 (sowing) |
| Potato | – | Apr 17–May 1 (transplant) | Jun 3–17 (transplant) |
| Sweet potato | – | Jun 5–19 (transplant) | – |
| Sweet corn | – | May 22–Jun 5 (sow outdoors) | – |
| Bean, bush (snap) | – | May 22–Jun 5 (sow outdoors) | – |
| Bean, pole | – | May 22–Jun 5 (sow outdoors) | – |
| Lima bean | – | May 29–Jun 12 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 5–26 (sow outdoors) | – |
| Cucumber | Apr 17–24 | May 22–Jun 5 (transplant) May 22–Jun 5 (sow outdoors) | – |
| Summer squash / zucchini | Apr 17–24 | May 22–Jun 5 (transplant) May 22–Jun 5 (sow outdoors) | – |
| Winter squash | Apr 17–24 | May 22–Jun 5 (transplant) May 22–Jun 5 (sow outdoors) | – |
| Pumpkin | – | May 22–Jun 5 (sow outdoors) | – |
| Watermelon | Apr 17–24 | May 29–Jun 12 (transplant) May 29–Jun 12 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 17–24 | May 29–Jun 12 (transplant) May 29–Jun 12 (sow outdoors) | – |
| Okra | Apr 3–17 | May 29–Jun 12 (transplant) May 29–Jun 12 (sow outdoors) | – |
| Celery | Feb 20–Mar 6 | May 22–29 (transplant) | – |
| Basil | Apr 3–17 | May 22–Jun 5 (transplant) May 22–Jun 5 (sow outdoors) | – |
| Cilantro | – | May 1–29 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Parsley | Mar 6–20 | May 1–15 (transplant) Apr 24–May 15 (sow outdoors) | – |
| Dill | – | May 15–29 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Sunflower | – | May 15–29 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 17–May 1 (transplant) | – |
| Rhubarb (crowns) | – | Apr 17–May 1 (transplant) | – |
| Strawberry (plants) | – | Apr 17–May 1 (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: Havre City Co AP, MT (NOAA GHCN-Daily ID USW00094012), elevation 2,585 ft, 10.2 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Ft Assiniboine, MT | 13 mi | May 15 | Sep 24 |
| Gildford, MT | 25 mi | May 24 | Sep 15 |
| Chinook, MT | 26 mi | May 14 | Sep 23 |
The average last-frost dates of these stations span 10 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59501
When is the last frost in 59501?
The average (50% chance) last spring freeze of 32°F for ZIP 59501 is May 15. For a more cautious planting date, use May 27, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59501?
The average first fall freeze is September 23. In 1 year in 10 it comes by September 11.
What hardiness zone is 59501?
ZIP 59501 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 59501 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
59532 Kremlin 59525 Gildford 59521 Rocky Boy's Agency 59523 Chinook 59528 Hingham 59540 Rudyard 59547 Zurich 59530 Inverness
Other ZIP codes in Hill County
59521 59525 59528 59530 59532 59540 All Hill County frost dates · Montana frost dates
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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.