Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 50521 (Webster County, 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, Ft Dodge 5NNW, IA (17 miles away).
- Average last spring frostApr 2850% chance of a 32°F freeze after this date
- Average first fall frostOct 850% chance of a 32°F freeze by this date
- Growing season (frost-free)162 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 50521, 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
53°F 50–55°F
24-hour average · latest 54°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Ames (30 mi).
4-inch depth
55°F 50–55°F
24-hour average · latest 55°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Ames (30 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 50521 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 55°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 13 |
| 50% (the "average" last frost) | Apr 28 |
| 10% (cautious: only 1 year in 10 freezes later) | May 9 |
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 24 |
| 50% (the "average" first frost) | Oct 8 |
| 90% (late: most years have frozen by now) | Oct 22 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 6 | Sep 30 |
| 32°F (freeze) | Apr 28 | Oct 8 |
| 28°F (hard freeze) | Apr 17 | Oct 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 50521
Dates count from your average last spring frost (Apr 28) and first fall frost (Oct 8). 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 3–17 | May 5–19 (transplant) | – |
| Pepper (sweet and hot) | Feb 17–Mar 3 | May 12–26 (transplant) | – |
| Eggplant | Feb 17–Mar 3 | May 12–26 (transplant) | – |
| Tomatillo | Mar 3–17 | May 5–19 (transplant) | – |
| Lettuce | Mar 3–17 | Apr 7–28 (transplant) Mar 31–May 12 (sow outdoors) | Aug 13–Sep 3 (transplant) Jul 30–Aug 27 (sowing) |
| Spinach | – | Mar 17–Apr 7 (sow outdoors) | Aug 13–Sep 3 (sowing) |
| Kale | Mar 3–17 | Mar 31–Apr 14 (transplant) Mar 31–Apr 14 (sow outdoors) | Jul 16–Aug 13 (transplant) Jul 2–30 (sowing) |
| Collards | Mar 3–17 | Mar 31–Apr 28 (transplant) Mar 31–Apr 28 (sow outdoors) | Jul 16–Aug 13 (transplant) Jul 2–30 (sowing) |
| Broccoli | Feb 17–Mar 3 | Mar 31–Apr 14 (transplant) | Jul 2–30 (transplant) |
| Cabbage | Feb 17–Mar 3 | Mar 31–Apr 14 (transplant) | Jul 2–30 (transplant) |
| Cauliflower | Feb 17–Mar 3 | Apr 14–28 (transplant) | Jul 2–30 (transplant) |
| Brussels sprouts | Feb 3–17 | Mar 31–Apr 14 (transplant) | Jun 18–Jul 9 (transplant) |
| Kohlrabi | Mar 3–17 | Mar 31–Apr 14 (transplant) Mar 31–Apr 14 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Bok choy / Asian greens | – | Mar 31–Apr 14 (sow outdoors) | Aug 13–27 (sowing) |
| Arugula | – | Mar 31–Apr 28 (sow outdoors) | Aug 13–Sep 10 (sowing) |
| Mustard greens | – | Mar 31–Apr 21 (sow outdoors) | Aug 13–27 (sowing) |
| Swiss chard | Mar 17–31 | Apr 14–May 5 (transplant) Apr 14–May 12 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Beet | – | Mar 31–Apr 28 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Carrot | – | Apr 7–May 5 (sow outdoors) | Jul 16–30 (sowing) |
| Radish | – | Mar 24–May 5 (sow outdoors) | Aug 27–Sep 10 (sowing) |
| Turnip | – | Mar 31–Apr 21 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Parsnip | – | Apr 7–28 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 3–31 (sow outdoors) | Jul 16–30 (sowing) |
| Onion (bulbing) | Feb 3–17 | Mar 17–31 (transplant) | – |
| Green onion / scallion | – | Mar 17–Apr 14 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Leek | Feb 3–17 | Mar 31–Apr 14 (transplant) | – |
| Garlic | – | – | Aug 27–Sep 24 (sowing) |
| Shallot | – | Mar 17–31 (transplant) | Aug 27–Sep 24 (sowing) |
| Potato | – | Mar 31–Apr 14 (transplant) | Jun 18–Jul 2 (transplant) |
| Sweet potato | – | May 19–Jun 2 (transplant) | – |
| Sweet corn | – | May 5–19 (sow outdoors) | – |
| Bean, bush (snap) | – | May 5–19 (sow outdoors) | – |
| Bean, pole | – | May 5–19 (sow outdoors) | – |
| Lima bean | – | May 12–26 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 19–Jun 9 (sow outdoors) | – |
| Cucumber | Mar 31–Apr 7 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Summer squash / zucchini | Mar 31–Apr 7 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Winter squash | Mar 31–Apr 7 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Pumpkin | – | May 5–19 (sow outdoors) | – |
| Watermelon | Mar 31–Apr 7 | May 12–26 (transplant) May 12–26 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 31–Apr 7 | May 12–26 (transplant) May 12–26 (sow outdoors) | – |
| Okra | Mar 17–31 | May 12–26 (transplant) May 12–26 (sow outdoors) | – |
| Celery | Feb 3–17 | May 5–12 (transplant) | – |
| Basil | Mar 17–31 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Cilantro | – | Apr 14–May 12 (sow outdoors) | Aug 13–27 (sowing) |
| Parsley | Feb 17–Mar 3 | Apr 14–28 (transplant) Apr 7–28 (sow outdoors) | – |
| Dill | – | Apr 28–May 12 (sow outdoors) | Aug 13–27 (sowing) |
| Sunflower | – | Apr 28–May 12 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 31–Apr 14 (transplant) | – |
| Rhubarb (crowns) | – | Mar 31–Apr 14 (transplant) | – |
| Strawberry (plants) | – | Mar 31–Apr 14 (transplant) | Jul 30–Aug 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: Ft Dodge 5NNW, IA (NOAA GHCN-Daily ID USC00132999), elevation 1,115 ft, 17.1 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Webster City, IA | 18 mi | May 3 | Oct 2 |
| Boone, IA | 24 mi | Apr 28 | Oct 12 |
| Humboldt WTP, IA | 26 mi | Apr 27 | Oct 9 |
The average last-frost dates of these stations span 7 days, a rough guide to local variation. See data sources & methods.
Frost questions for 50521
When is the last frost in 50521?
The average (50% chance) last spring freeze of 32°F for ZIP 50521 is April 28. For a more cautious planting date, use May 9, when only 1 year in 10 still sees a later freeze.
When is the first frost in 50521?
The average first fall freeze is October 8. In 1 year in 10 it comes by September 24.
What hardiness zone is 50521?
ZIP 50521 is in USDA zone 5a (-20 to -15°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 50521 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
50557 Lehigh 50569 Otho 50530 Dayton 50544 Harcourt 50532 Duncombe 50523 Callender 50501 Fort Dodge 50249 Stratford
Other ZIP codes in Webster County
50501 50516 50518 50523 50524 50530 50532 50543 50544 50557 50566 50569 50594 All Webster County frost dates · Iowa 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.