Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 50641 (Hazleton, 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, Oelwein 2 S, IA (4 miles away).
- Average last spring frostApr 3050% chance of a 32°F freeze after this date
- Average first fall frostOct 950% chance of a 32°F freeze by this date
- Growing season (frost-free)163 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
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 50641 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 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 14 |
| 50% (the "average" last frost) | Apr 30 |
| 10% (cautious: only 1 year in 10 freezes later) | May 13 |
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 26 |
| 50% (the "average" first frost) | Oct 9 |
| 90% (late: most years have frozen by now) | Oct 20 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 8 | Oct 1 |
| 32°F (freeze) | Apr 30 | Oct 9 |
| 28°F (hard freeze) | Apr 19 | 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 50641
Dates count from your average last spring frost (Apr 30) and first fall frost (Oct 9). 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 5–19 | May 7–21 (transplant) | – |
| Pepper (sweet and hot) | Feb 19–Mar 5 | May 14–28 (transplant) | – |
| Eggplant | Feb 19–Mar 5 | May 14–28 (transplant) | – |
| Tomatillo | Mar 5–19 | May 7–21 (transplant) | – |
| Lettuce | Mar 5–19 | Apr 9–30 (transplant) Apr 2–May 14 (sow outdoors) | Aug 14–Sep 4 (transplant) Jul 31–Aug 28 (sowing) |
| Spinach | – | Mar 19–Apr 9 (sow outdoors) | Aug 14–Sep 4 (sowing) |
| Kale | Mar 5–19 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | Jul 17–Aug 14 (transplant) Jul 3–31 (sowing) |
| Collards | Mar 5–19 | Apr 2–30 (transplant) Apr 2–30 (sow outdoors) | Jul 17–Aug 14 (transplant) Jul 3–31 (sowing) |
| Broccoli | Feb 19–Mar 5 | Apr 2–16 (transplant) | Jul 3–31 (transplant) |
| Cabbage | Feb 19–Mar 5 | Apr 2–16 (transplant) | Jul 3–31 (transplant) |
| Cauliflower | Feb 19–Mar 5 | Apr 16–30 (transplant) | Jul 3–31 (transplant) |
| Brussels sprouts | Feb 5–19 | Apr 2–16 (transplant) | Jun 19–Jul 10 (transplant) |
| Kohlrabi | Mar 5–19 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Bok choy / Asian greens | – | Apr 2–16 (sow outdoors) | Aug 14–28 (sowing) |
| Arugula | – | Apr 2–30 (sow outdoors) | Aug 14–Sep 11 (sowing) |
| Mustard greens | – | Apr 2–23 (sow outdoors) | Aug 14–28 (sowing) |
| Swiss chard | Mar 19–Apr 2 | Apr 16–May 7 (transplant) Apr 16–May 14 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Beet | – | Apr 2–30 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Carrot | – | Apr 9–May 7 (sow outdoors) | Jul 17–31 (sowing) |
| Radish | – | Mar 26–May 7 (sow outdoors) | Aug 28–Sep 11 (sowing) |
| Turnip | – | Apr 2–23 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Parsnip | – | Apr 9–30 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 5–Apr 2 (sow outdoors) | Jul 17–31 (sowing) |
| Onion (bulbing) | Feb 5–19 | Mar 19–Apr 2 (transplant) | – |
| Green onion / scallion | – | Mar 19–Apr 16 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Leek | Feb 5–19 | Apr 2–16 (transplant) | – |
| Garlic | – | – | Aug 28–Sep 25 (sowing) |
| Shallot | – | Mar 19–Apr 2 (transplant) | Aug 28–Sep 25 (sowing) |
| Potato | – | Apr 2–16 (transplant) | Jun 19–Jul 3 (transplant) |
| Sweet potato | – | May 21–Jun 4 (transplant) | – |
| Sweet corn | – | May 7–21 (sow outdoors) | – |
| Bean, bush (snap) | – | May 7–21 (sow outdoors) | – |
| Bean, pole | – | May 7–21 (sow outdoors) | – |
| Lima bean | – | May 14–28 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 21–Jun 11 (sow outdoors) | – |
| Cucumber | Apr 2–9 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Summer squash / zucchini | Apr 2–9 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Winter squash | Apr 2–9 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Pumpkin | – | May 7–21 (sow outdoors) | – |
| Watermelon | Apr 2–9 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 2–9 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Okra | Mar 19–Apr 2 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Celery | Feb 5–19 | May 7–14 (transplant) | – |
| Basil | Mar 19–Apr 2 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Cilantro | – | Apr 16–May 14 (sow outdoors) | Aug 14–28 (sowing) |
| Parsley | Feb 19–Mar 5 | Apr 16–30 (transplant) Apr 9–30 (sow outdoors) | – |
| Dill | – | Apr 30–May 14 (sow outdoors) | Aug 14–28 (sowing) |
| Sunflower | – | Apr 30–May 14 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 2–16 (transplant) | – |
| Rhubarb (crowns) | – | Apr 2–16 (transplant) | – |
| Strawberry (plants) | – | Apr 2–16 (transplant) | Jul 31–Aug 28 (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: Oelwein 2 S, IA (NOAA GHCN-Daily ID USC00136200), elevation 1,010 ft, 3.8 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Stanley, IA | 4 mi | May 4 | Oct 1 |
| Independence #1, IA | 5 mi | Apr 30 | Oct 7 |
| Oelwein 1E, IA | 7 mi | Apr 27 | Oct 13 |
The average last-frost dates of these stations span 8 days, a rough guide to local variation. See data sources & methods.
Frost questions for 50641
When is the last frost in 50641?
The average (50% chance) last spring freeze of 32°F for ZIP 50641 is April 30. For a more cautious planting date, use May 13, when only 1 year in 10 still sees a later freeze.
When is the first frost in 50641?
The average first fall freeze is October 9. In 1 year in 10 it comes by September 26.
What hardiness zone is 50641?
ZIP 50641 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 50641 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
50662 Oelwein 50671 Stanley 50644 Independence 50629 Fairbank 50607 Aurora 50664 50655 Maynard 50626 Dunkerton
Other ZIP codes in Buchanan County
50607 50629 50644 50650 50654 50682 52210 52326 52329 All Buchanan 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.