Fall in zone 5bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 51647 (Northboro, IA)
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, Shenandoah, IA (11 miles away).
- Average last spring frostApr 2050% chance of a 32°F freeze after this date
- Average first fall frostOct 1750% chance of a 32°F freeze by this date
- Growing season (frost-free)179 daysmedian, 32°F threshold
- USDA hardiness zone5b-15 to -10°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 51647, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
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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
52°F 50–55°F
24-hour average · latest 52°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Rogers Farm #1 (61 mi).
4-inch depth
53°F 50–55°F
24-hour average · latest 53°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Rogers Farm #1 (61 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 51647 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 53°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 early May).
Fertilizer window
Lawn region: North (cool-season). 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 5 |
| 50% (the "average" last frost) | Apr 20 |
| 10% (cautious: only 1 year in 10 freezes later) | May 3 |
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) | Oct 1 |
| 50% (the "average" first frost) | Oct 17 |
| 90% (late: most years have frozen by now) | Oct 29 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Apr 30 | Oct 6 |
| 32°F (freeze) | Apr 20 | Oct 17 |
| 28°F (hard freeze) | Apr 9 | Oct 26 |
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 51647
Dates count from your average last spring frost (Apr 20) and first fall frost (Oct 17). 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 | Feb 23–Mar 9 | Apr 27–May 11 (transplant) | – |
| Pepper (sweet and hot) | Feb 9–23 | May 4–18 (transplant) | – |
| Eggplant | Feb 9–23 | May 4–18 (transplant) | – |
| Tomatillo | Feb 23–Mar 9 | Apr 27–May 11 (transplant) | – |
| Lettuce | Feb 23–Mar 9 | Mar 30–Apr 20 (transplant) Mar 23–May 4 (sow outdoors) | Aug 22–Sep 12 (transplant) Aug 8–Sep 5 (sowing) |
| Spinach | – | Mar 9–30 (sow outdoors) | Aug 22–Sep 12 (sowing) |
| Kale | Feb 23–Mar 9 | Mar 23–Apr 6 (transplant) Mar 23–Apr 6 (sow outdoors) | Jul 25–Aug 22 (transplant) Jul 11–Aug 8 (sowing) |
| Collards | Feb 23–Mar 9 | Mar 23–Apr 20 (transplant) Mar 23–Apr 20 (sow outdoors) | Jul 25–Aug 22 (transplant) Jul 11–Aug 8 (sowing) |
| Broccoli | Feb 9–23 | Mar 23–Apr 6 (transplant) | Jul 11–Aug 8 (transplant) |
| Cabbage | Feb 9–23 | Mar 23–Apr 6 (transplant) | Jul 11–Aug 8 (transplant) |
| Cauliflower | Feb 9–23 | Apr 6–20 (transplant) | Jul 11–Aug 8 (transplant) |
| Brussels sprouts | Jan 26–Feb 9 | Mar 23–Apr 6 (transplant) | Jun 27–Jul 18 (transplant) |
| Kohlrabi | Feb 23–Mar 9 | Mar 23–Apr 6 (transplant) Mar 23–Apr 6 (sow outdoors) | Aug 8–22 (sowing) |
| Bok choy / Asian greens | – | Mar 23–Apr 6 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Arugula | – | Mar 23–Apr 20 (sow outdoors) | Aug 22–Sep 19 (sowing) |
| Mustard greens | – | Mar 23–Apr 13 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Swiss chard | Mar 9–23 | Apr 6–27 (transplant) Apr 6–May 4 (sow outdoors) | Aug 8–22 (sowing) |
| Beet | – | Mar 23–Apr 20 (sow outdoors) | Aug 8–22 (sowing) |
| Carrot | – | Mar 30–Apr 27 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Radish | – | Mar 16–Apr 27 (sow outdoors) | Sep 5–19 (sowing) |
| Turnip | – | Mar 23–Apr 13 (sow outdoors) | Aug 8–22 (sowing) |
| Parsnip | – | Mar 30–Apr 20 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Feb 23–Mar 23 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Onion (bulbing) | Jan 26–Feb 9 | Mar 9–23 (transplant) | – |
| Green onion / scallion | – | Mar 9–Apr 6 (sow outdoors) | Aug 8–22 (sowing) |
| Leek | Jan 26–Feb 9 | Mar 23–Apr 6 (transplant) | – |
| Garlic | – | – | Sep 5–Oct 3 (sowing) |
| Shallot | – | Mar 9–23 (transplant) | Sep 5–Oct 3 (sowing) |
| Potato | – | Mar 23–Apr 6 (transplant) | Jun 27–Jul 11 (transplant) |
| Sweet potato | – | May 11–25 (transplant) | – |
| Sweet corn | – | Apr 27–May 11 (sow outdoors) | – |
| Bean, bush (snap) | – | Apr 27–May 11 (sow outdoors) | – |
| Bean, pole | – | Apr 27–May 11 (sow outdoors) | – |
| Lima bean | – | May 4–18 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 11–Jun 1 (sow outdoors) | – |
| Cucumber | Mar 23–30 | Apr 27–May 11 (transplant) Apr 27–May 11 (sow outdoors) | – |
| Summer squash / zucchini | Mar 23–30 | Apr 27–May 11 (transplant) Apr 27–May 11 (sow outdoors) | – |
| Winter squash | Mar 23–30 | Apr 27–May 11 (transplant) Apr 27–May 11 (sow outdoors) | – |
| Pumpkin | – | Apr 27–May 11 (sow outdoors) | – |
| Watermelon | Mar 23–30 | May 4–18 (transplant) May 4–18 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 23–30 | May 4–18 (transplant) May 4–18 (sow outdoors) | – |
| Okra | Mar 9–23 | May 4–18 (transplant) May 4–18 (sow outdoors) | – |
| Celery | Jan 26–Feb 9 | Apr 27–May 4 (transplant) | – |
| Basil | Mar 9–23 | Apr 27–May 11 (transplant) Apr 27–May 11 (sow outdoors) | – |
| Cilantro | – | Apr 6–May 4 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Parsley | Feb 9–23 | Apr 6–20 (transplant) Mar 30–Apr 20 (sow outdoors) | – |
| Dill | – | Apr 20–May 4 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Sunflower | – | Apr 20–May 4 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 23–Apr 6 (transplant) | – |
| Rhubarb (crowns) | – | Mar 23–Apr 6 (transplant) | – |
| Strawberry (plants) | – | Mar 23–Apr 6 (transplant) | Aug 8–Sep 5 (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: Shenandoah, IA (NOAA GHCN-Daily ID USC00137613), elevation 999 ft, 11.5 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Tarkio, MO | 12 mi | Apr 19 | Oct 15 |
| Sidney 1SSE, IA | 18 mi | Apr 19 | Oct 19 |
| Clarinda, IA | 19 mi | Apr 25 | Oct 11 |
The average last-frost dates of these stations span 6 days, a rough guide to local variation. See data sources & methods.
Frost questions for 51647
When is the last frost in 51647?
The average (50% chance) last spring freeze of 32°F for ZIP 51647 is April 20. For a more cautious planting date, use May 3, when only 1 year in 10 still sees a later freeze.
When is the first frost in 51647?
The average first fall freeze is October 17. In 1 year in 10 it comes by October 1.
What hardiness zone is 51647?
ZIP 51647 is in USDA zone 5b (-15 to -10°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 51647 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
64498 Blanchard 51636 Coin 51630 Blanchard 51601 Shenandoah 51639 Farragut 64491 Tarkio 64445 Elmo 51650 Riverton
Other ZIP codes in Page County
51601 51630 51631 51632 51636 51637 51638 51651 51656 All Page County frost dates · Iowa 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.