Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 51104 (Sioux City, 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, Sioux City Ang, IA (10 miles away).
- Average last spring frostApr 2950% chance of a 32°F freeze after this date
- Average first fall frostOct 750% chance of a 32°F freeze by this date
- Growing season (frost-free)161 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°F avg. coldest night
Get The Dial for 51104 (Sioux City)
Frost and freeze alerts from the NWS forecast for 51104, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
- Freeze alerts
- Soil-temp heads-up
- Weekly yard to-dos
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.
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 53°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Shagbark Hills (33 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 Shagbark Hills (33 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 51104 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 15 |
| 50% (the "average" last frost) | Apr 29 |
| 10% (cautious: only 1 year in 10 freezes later) | May 11 |
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 7 |
| 90% (late: most years have frozen by now) | Oct 21 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 7 | Sep 29 |
| 32°F (freeze) | Apr 29 | Oct 7 |
| 28°F (hard freeze) | Apr 19 | Oct 18 |
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 51104
Dates count from your average last spring frost (Apr 29) and first fall frost (Oct 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 | Mar 4–18 | May 6–20 (transplant) | – |
| Pepper (sweet and hot) | Feb 18–Mar 4 | May 13–27 (transplant) | – |
| Eggplant | Feb 18–Mar 4 | May 13–27 (transplant) | – |
| Tomatillo | Mar 4–18 | May 6–20 (transplant) | – |
| Lettuce | Mar 4–18 | Apr 8–29 (transplant) Apr 1–May 13 (sow outdoors) | Aug 12–Sep 2 (transplant) Jul 29–Aug 26 (sowing) |
| Spinach | – | Mar 18–Apr 8 (sow outdoors) | Aug 12–Sep 2 (sowing) |
| Kale | Mar 4–18 | Apr 1–15 (transplant) Apr 1–15 (sow outdoors) | Jul 15–Aug 12 (transplant) Jul 1–29 (sowing) |
| Collards | Mar 4–18 | Apr 1–29 (transplant) Apr 1–29 (sow outdoors) | Jul 15–Aug 12 (transplant) Jul 1–29 (sowing) |
| Broccoli | Feb 18–Mar 4 | Apr 1–15 (transplant) | Jul 1–29 (transplant) |
| Cabbage | Feb 18–Mar 4 | Apr 1–15 (transplant) | Jul 1–29 (transplant) |
| Cauliflower | Feb 18–Mar 4 | Apr 15–29 (transplant) | Jul 1–29 (transplant) |
| Brussels sprouts | Feb 4–18 | Apr 1–15 (transplant) | Jun 17–Jul 8 (transplant) |
| Kohlrabi | Mar 4–18 | Apr 1–15 (transplant) Apr 1–15 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Bok choy / Asian greens | – | Apr 1–15 (sow outdoors) | Aug 12–26 (sowing) |
| Arugula | – | Apr 1–29 (sow outdoors) | Aug 12–Sep 9 (sowing) |
| Mustard greens | – | Apr 1–22 (sow outdoors) | Aug 12–26 (sowing) |
| Swiss chard | Mar 18–Apr 1 | Apr 15–May 6 (transplant) Apr 15–May 13 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Beet | – | Apr 1–29 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Carrot | – | Apr 8–May 6 (sow outdoors) | Jul 15–29 (sowing) |
| Radish | – | Mar 25–May 6 (sow outdoors) | Aug 26–Sep 9 (sowing) |
| Turnip | – | Apr 1–22 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Parsnip | – | Apr 8–29 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 4–Apr 1 (sow outdoors) | Jul 15–29 (sowing) |
| Onion (bulbing) | Feb 4–18 | Mar 18–Apr 1 (transplant) | – |
| Green onion / scallion | – | Mar 18–Apr 15 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Leek | Feb 4–18 | Apr 1–15 (transplant) | – |
| Garlic | – | – | Aug 26–Sep 23 (sowing) |
| Shallot | – | Mar 18–Apr 1 (transplant) | Aug 26–Sep 23 (sowing) |
| Potato | – | Apr 1–15 (transplant) | Jun 17–Jul 1 (transplant) |
| Sweet potato | – | May 20–Jun 3 (transplant) | – |
| Sweet corn | – | May 6–20 (sow outdoors) | – |
| Bean, bush (snap) | – | May 6–20 (sow outdoors) | – |
| Bean, pole | – | May 6–20 (sow outdoors) | – |
| Lima bean | – | May 13–27 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 20–Jun 10 (sow outdoors) | – |
| Cucumber | Apr 1–8 | May 6–20 (transplant) May 6–20 (sow outdoors) | – |
| Summer squash / zucchini | Apr 1–8 | May 6–20 (transplant) May 6–20 (sow outdoors) | – |
| Winter squash | Apr 1–8 | May 6–20 (transplant) May 6–20 (sow outdoors) | – |
| Pumpkin | – | May 6–20 (sow outdoors) | – |
| Watermelon | Apr 1–8 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 1–8 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Okra | Mar 18–Apr 1 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Celery | Feb 4–18 | May 6–13 (transplant) | – |
| Basil | Mar 18–Apr 1 | May 6–20 (transplant) May 6–20 (sow outdoors) | – |
| Cilantro | – | Apr 15–May 13 (sow outdoors) | Aug 12–26 (sowing) |
| Parsley | Feb 18–Mar 4 | Apr 15–29 (transplant) Apr 8–29 (sow outdoors) | – |
| Dill | – | Apr 29–May 13 (sow outdoors) | Aug 12–26 (sowing) |
| Sunflower | – | Apr 29–May 13 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 1–15 (transplant) | – |
| Rhubarb (crowns) | – | Apr 1–15 (transplant) | – |
| Strawberry (plants) | – | Apr 1–15 (transplant) | Jul 29–Aug 26 (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: Sioux City Ang, IA (NOAA GHCN-Daily ID USC00137702), elevation 1,100 ft, 9.6 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Sioux City Gateway AP, IA | 10 mi | Apr 29 | Oct 5 |
| Le Mars, IA | 21 mi | Apr 30 | Oct 4 |
| Walthill 1E, NE | 27 mi | May 1 | Oct 6 |
The average last-frost dates of these stations span 3 days, a rough guide to local variation. See data sources & methods.
Frost questions for 51104
When is the last frost in 51104?
The average (50% chance) last spring freeze of 32°F for ZIP 51104 is April 29. For a more cautious planting date, use May 11, when only 1 year in 10 still sees a later freeze.
When is the first frost in 51104?
The average first fall freeze is October 7. In 1 year in 10 it comes by September 24.
What hardiness zone is 51104?
ZIP 51104 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 51104 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
51103 Sioux City 51105 Sioux City 51101 Sioux City 51108 Sioux City 57049 North Sioux City 68776 South Sioux City 51109 Sioux City 51106 Sioux City
Other ZIP codes in Woodbury County
51004 51007 51015 51016 51019 51026 51030 51039 51044 51048 51052 51054 51055 51056 51101 51103 51105 51106 51111 All Woodbury County frost dates · Iowa frost dates
Never miss a frost: get The Dial
Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
- Soil-temp heads-up
- Weekly yard to-dos
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.