Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 50117 (Audubon 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, Audubon, IA (7 miles away).
- Average last spring frostMay 250% chance of a 32°F freeze after this date
- Average first fall frostOct 350% chance of a 32°F freeze by this date
- Growing season (frost-free)154 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°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
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 (59 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 (59 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 50117 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 19 |
| 50% (the "average" last frost) | May 2 |
| 10% (cautious: only 1 year in 10 freezes later) | May 15 |
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 19 |
| 50% (the "average" first frost) | Oct 3 |
| 90% (late: most years have frozen by now) | Oct 17 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 10 | Sep 25 |
| 32°F (freeze) | May 2 | Oct 3 |
| 28°F (hard freeze) | Apr 22 | Oct 14 |
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 50117
Dates count from your average last spring frost (May 2) and first fall frost (Oct 3). 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 7–21 | May 9–23 (transplant) | – |
| Pepper (sweet and hot) | Feb 21–Mar 7 | May 16–30 (transplant) | – |
| Eggplant | Feb 21–Mar 7 | May 16–30 (transplant) | – |
| Tomatillo | Mar 7–21 | May 9–23 (transplant) | – |
| Lettuce | Mar 7–21 | Apr 11–May 2 (transplant) Apr 4–May 16 (sow outdoors) | Aug 8–29 (transplant) Jul 25–Aug 22 (sowing) |
| Spinach | – | Mar 21–Apr 11 (sow outdoors) | Aug 8–29 (sowing) |
| Kale | Mar 7–21 | Apr 4–18 (transplant) Apr 4–18 (sow outdoors) | Jul 11–Aug 8 (transplant) Jun 27–Jul 25 (sowing) |
| Collards | Mar 7–21 | Apr 4–May 2 (transplant) Apr 4–May 2 (sow outdoors) | Jul 11–Aug 8 (transplant) Jun 27–Jul 25 (sowing) |
| Broccoli | Feb 21–Mar 7 | Apr 4–18 (transplant) | Jun 27–Jul 25 (transplant) |
| Cabbage | Feb 21–Mar 7 | Apr 4–18 (transplant) | Jun 27–Jul 25 (transplant) |
| Cauliflower | Feb 21–Mar 7 | Apr 18–May 2 (transplant) | Jun 27–Jul 25 (transplant) |
| Brussels sprouts | Feb 7–21 | Apr 4–18 (transplant) | Jun 13–Jul 4 (transplant) |
| Kohlrabi | Mar 7–21 | Apr 4–18 (transplant) Apr 4–18 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Bok choy / Asian greens | – | Apr 4–18 (sow outdoors) | Aug 8–22 (sowing) |
| Arugula | – | Apr 4–May 2 (sow outdoors) | Aug 8–Sep 5 (sowing) |
| Mustard greens | – | Apr 4–25 (sow outdoors) | Aug 8–22 (sowing) |
| Swiss chard | Mar 21–Apr 4 | Apr 18–May 9 (transplant) Apr 18–May 16 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Beet | – | Apr 4–May 2 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Carrot | – | Apr 11–May 9 (sow outdoors) | Jul 11–25 (sowing) |
| Radish | – | Mar 28–May 9 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Turnip | – | Apr 4–25 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Parsnip | – | Apr 11–May 2 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 7–Apr 4 (sow outdoors) | Jul 11–25 (sowing) |
| Onion (bulbing) | Feb 7–21 | Mar 21–Apr 4 (transplant) | – |
| Green onion / scallion | – | Mar 21–Apr 18 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Leek | Feb 7–21 | Apr 4–18 (transplant) | – |
| Garlic | – | – | Aug 22–Sep 19 (sowing) |
| Shallot | – | Mar 21–Apr 4 (transplant) | Aug 22–Sep 19 (sowing) |
| Potato | – | Apr 4–18 (transplant) | Jun 13–27 (transplant) |
| Sweet potato | – | May 23–Jun 6 (transplant) | – |
| Sweet corn | – | May 9–23 (sow outdoors) | – |
| Bean, bush (snap) | – | May 9–23 (sow outdoors) | – |
| Bean, pole | – | May 9–23 (sow outdoors) | – |
| Lima bean | – | May 16–30 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 23–Jun 13 (sow outdoors) | – |
| Cucumber | Apr 4–11 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Summer squash / zucchini | Apr 4–11 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Winter squash | Apr 4–11 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Pumpkin | – | May 9–23 (sow outdoors) | – |
| Watermelon | Apr 4–11 | May 16–30 (transplant) May 16–30 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 4–11 | May 16–30 (transplant) May 16–30 (sow outdoors) | – |
| Okra | Mar 21–Apr 4 | May 16–30 (transplant) May 16–30 (sow outdoors) | – |
| Celery | Feb 7–21 | May 9–16 (transplant) | – |
| Basil | Mar 21–Apr 4 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Cilantro | – | Apr 18–May 16 (sow outdoors) | Aug 8–22 (sowing) |
| Parsley | Feb 21–Mar 7 | Apr 18–May 2 (transplant) Apr 11–May 2 (sow outdoors) | – |
| Dill | – | May 2–16 (sow outdoors) | Aug 8–22 (sowing) |
| Sunflower | – | May 2–16 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 4–18 (transplant) | – |
| Rhubarb (crowns) | – | Apr 4–18 (transplant) | – |
| Strawberry (plants) | – | Apr 4–18 (transplant) | Jul 25–Aug 22 (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: Audubon, IA (NOAA GHCN-Daily ID USC00130385), elevation 1,280 ft, 7.0 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Guthrie Ctr, IA | 15 mi | May 2 | Oct 3 |
| Atlantic 1 NE, IA | 21 mi | Apr 30 | Oct 2 |
| Carroll, IA | 27 mi | Apr 27 | Oct 10 |
The average last-frost dates of these stations span 6 days, a rough guide to local variation. See data sources & methods.
Frost questions for 50117
When is the last frost in 50117?
The average (50% chance) last spring freeze of 32°F for ZIP 50117 is May 2. For a more cautious planting date, use May 15, when only 1 year in 10 still sees a later freeze.
When is the first frost in 50117?
The average first fall freeze is October 3. In 1 year in 10 it comes by September 19.
What hardiness zone is 50117?
ZIP 50117 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 50117 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
50076 Exira 50025 Audubon 50042 Brayton 50115 Guthrie Center 50058 Coon Rapids 50002 Adair 51543 Kimballton 50110 Gray
Other ZIP codes in Audubon County
50025 50042 50076 50110 51543 All Audubon 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.