Fall in zone 4bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59401 (Great Falls, 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, Great Falls 16ST, MT (2 miles away).
- Average last spring frostMay 650% chance of a 32°F freeze after this date
- Average first fall frostOct 150% chance of a 32°F freeze by this date
- Growing season (frost-free)147 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 59401 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) | Apr 23 |
| 50% (the "average" last frost) | May 6 |
| 10% (cautious: only 1 year in 10 freezes later) | May 19 |
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 17 |
| 50% (the "average" first frost) | Oct 1 |
| 90% (late: most years have frozen by now) | Oct 16 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 19 | Sep 21 |
| 32°F (freeze) | May 6 | Oct 1 |
| 28°F (hard freeze) | Apr 24 | Oct 11 |
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 59401
Dates count from your average last spring frost (May 6) and first fall frost (Oct 1). 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 11–25 | May 13–27 (transplant) | – |
| Pepper (sweet and hot) | Feb 25–Mar 11 | May 20–Jun 3 (transplant) | – |
| Eggplant | Feb 25–Mar 11 | May 20–Jun 3 (transplant) | – |
| Tomatillo | Mar 11–25 | May 13–27 (transplant) | – |
| Lettuce | Mar 11–25 | Apr 15–May 6 (transplant) Apr 8–May 20 (sow outdoors) | Aug 6–27 (transplant) Jul 23–Aug 20 (sowing) |
| Spinach | – | Mar 25–Apr 15 (sow outdoors) | Aug 6–27 (sowing) |
| Kale | Mar 11–25 | Apr 8–22 (transplant) Apr 8–22 (sow outdoors) | Jul 9–Aug 6 (transplant) Jun 25–Jul 23 (sowing) |
| Collards | Mar 11–25 | Apr 8–May 6 (transplant) Apr 8–May 6 (sow outdoors) | Jul 9–Aug 6 (transplant) Jun 25–Jul 23 (sowing) |
| Broccoli | Feb 25–Mar 11 | Apr 8–22 (transplant) | Jun 25–Jul 23 (transplant) |
| Cabbage | Feb 25–Mar 11 | Apr 8–22 (transplant) | Jun 25–Jul 23 (transplant) |
| Cauliflower | Feb 25–Mar 11 | Apr 22–May 6 (transplant) | Jun 25–Jul 23 (transplant) |
| Brussels sprouts | Feb 11–25 | Apr 8–22 (transplant) | Jun 11–Jul 2 (transplant) |
| Kohlrabi | Mar 11–25 | Apr 8–22 (transplant) Apr 8–22 (sow outdoors) | Jul 23–Aug 6 (sowing) |
| Bok choy / Asian greens | – | Apr 8–22 (sow outdoors) | Aug 6–20 (sowing) |
| Arugula | – | Apr 8–May 6 (sow outdoors) | Aug 6–Sep 3 (sowing) |
| Mustard greens | – | Apr 8–29 (sow outdoors) | Aug 6–20 (sowing) |
| Swiss chard | Mar 25–Apr 8 | Apr 22–May 13 (transplant) Apr 22–May 20 (sow outdoors) | Jul 23–Aug 6 (sowing) |
| Beet | – | Apr 8–May 6 (sow outdoors) | Jul 23–Aug 6 (sowing) |
| Carrot | – | Apr 15–May 13 (sow outdoors) | Jul 9–23 (sowing) |
| Radish | – | Apr 1–May 13 (sow outdoors) | Aug 20–Sep 3 (sowing) |
| Turnip | – | Apr 8–29 (sow outdoors) | Jul 23–Aug 6 (sowing) |
| Parsnip | – | Apr 15–May 6 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 11–Apr 8 (sow outdoors) | Jul 9–23 (sowing) |
| Onion (bulbing) | Feb 11–25 | Mar 25–Apr 8 (transplant) | – |
| Green onion / scallion | – | Mar 25–Apr 22 (sow outdoors) | Jul 23–Aug 6 (sowing) |
| Leek | Feb 11–25 | Apr 8–22 (transplant) | – |
| Garlic | – | – | Aug 20–Sep 17 (sowing) |
| Shallot | – | Mar 25–Apr 8 (transplant) | Aug 20–Sep 17 (sowing) |
| Potato | – | Apr 8–22 (transplant) | Jun 11–25 (transplant) |
| Sweet potato | – | May 27–Jun 10 (transplant) | – |
| Sweet corn | – | May 13–27 (sow outdoors) | – |
| Bean, bush (snap) | – | May 13–27 (sow outdoors) | – |
| Bean, pole | – | May 13–27 (sow outdoors) | – |
| Lima bean | – | May 20–Jun 3 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 27–Jun 17 (sow outdoors) | – |
| Cucumber | Apr 8–15 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Summer squash / zucchini | Apr 8–15 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Winter squash | Apr 8–15 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Pumpkin | – | May 13–27 (sow outdoors) | – |
| Watermelon | Apr 8–15 | May 20–Jun 3 (transplant) May 20–Jun 3 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 8–15 | May 20–Jun 3 (transplant) May 20–Jun 3 (sow outdoors) | – |
| Okra | Mar 25–Apr 8 | May 20–Jun 3 (transplant) May 20–Jun 3 (sow outdoors) | – |
| Celery | Feb 11–25 | May 13–20 (transplant) | – |
| Basil | Mar 25–Apr 8 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Cilantro | – | Apr 22–May 20 (sow outdoors) | Aug 6–20 (sowing) |
| Parsley | Feb 25–Mar 11 | Apr 22–May 6 (transplant) Apr 15–May 6 (sow outdoors) | – |
| Dill | – | May 6–20 (sow outdoors) | Aug 6–20 (sowing) |
| Sunflower | – | May 6–20 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 8–22 (transplant) | – |
| Rhubarb (crowns) | – | Apr 8–22 (transplant) | – |
| Strawberry (plants) | – | Apr 8–22 (transplant) | Jul 23–Aug 20 (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: Great Falls 16ST, MT (NOAA GHCN-Daily ID USC00243749), elevation 3,505 ft, 1.6 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Great Falls Intl AP, MT | 6 mi | May 19 | Sep 24 |
| Great Falls WFO, MT | 6 mi | May 12 | Sep 28 |
| Carter 14 W, MT | 20 mi | May 23 | Sep 23 |
The average last-frost dates of these stations span 17 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59401
When is the last frost in 59401?
The average (50% chance) last spring freeze of 32°F for ZIP 59401 is May 6. For a more cautious planting date, use May 19, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59401?
The average first fall freeze is October 1. In 1 year in 10 it comes by September 17.
What hardiness zone is 59401?
ZIP 59401 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 59401 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
59414 Black Eagle 59404 Sun Prairie 59472 Sand Coulee 59485 Ulm 59440 Floweree 59405 Malmstrom AFB 59487 Vaughn 59483 Sun River
Other ZIP codes in Cascade County
59404 59405 59412 59414 59421 59443 59463 59465 59472 59477 59480 59483 59485 59487 All Cascade 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.