Fall in zone 6aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 66955 (Mahaska, KS)
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, Fairbury 5S, NE (10 miles away).
- Average last spring frostApr 2550% chance of a 32°F freeze after this date
- Average first fall frostOct 1550% chance of a 32°F freeze by this date
- Growing season (frost-free)169 daysmedian, 32°F threshold
- USDA hardiness zone6a-10 to -5°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
51°F 50–55°F
24-hour average · latest 51°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Lincoln 11 SW (56 mi).
4-inch depth
54°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 Lincoln 11 SW (56 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 66955 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 54°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 early March to early April).
Fertilizer window
Lawn region: Transition zone. Timing only; always follow the product label.
- Bermudagrass (warm-season): Spring: Several weeks after the lawn is fully green (April–May) (about Jun 10 here, using green-up about 3–4 weeks after your average last frost); Summer: Every 4–6 weeks through mid-August (heaviest feeder of the group); Late: Light, low-nitrogen/high-potassium feeding about 4 weeks before first frost, or skip. Avoid: Heavy late-fall nitrogen (linked to spring dead spot).
- Tall fescue (cool-season): Early fall: September (main feeding); Late fall: November, while still green; Late winter: Optional light feeding February–March. Avoid: Feeding after mid-spring and through summer in the transition zone (stress and brown patch).
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 9 |
| 50% (the "average" last frost) | Apr 25 |
| 10% (cautious: only 1 year in 10 freezes later) | May 7 |
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 30 |
| 50% (the "average" first frost) | Oct 15 |
| 90% (late: most years have frozen by now) | Oct 26 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 3 | Oct 5 |
| 32°F (freeze) | Apr 25 | Oct 15 |
| 28°F (hard freeze) | Apr 14 | Oct 24 |
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 66955
Dates count from your average last spring frost (Apr 25) and first fall frost (Oct 15). 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 28–Mar 14 | May 2–16 (transplant) | – |
| Pepper (sweet and hot) | Feb 14–28 | May 9–23 (transplant) | – |
| Eggplant | Feb 14–28 | May 9–23 (transplant) | – |
| Tomatillo | Feb 28–Mar 14 | May 2–16 (transplant) | – |
| Lettuce | Feb 28–Mar 14 | Apr 4–25 (transplant) Mar 28–May 9 (sow outdoors) | Aug 20–Sep 10 (transplant) Aug 6–Sep 3 (sowing) |
| Spinach | – | Mar 14–Apr 4 (sow outdoors) | Aug 20–Sep 10 (sowing) |
| Kale | Feb 28–Mar 14 | Mar 28–Apr 11 (transplant) Mar 28–Apr 11 (sow outdoors) | Jul 23–Aug 20 (transplant) Jul 9–Aug 6 (sowing) |
| Collards | Feb 28–Mar 14 | Mar 28–Apr 25 (transplant) Mar 28–Apr 25 (sow outdoors) | Jul 23–Aug 20 (transplant) Jul 9–Aug 6 (sowing) |
| Broccoli | Feb 14–28 | Mar 28–Apr 11 (transplant) | Jul 9–Aug 6 (transplant) |
| Cabbage | Feb 14–28 | Mar 28–Apr 11 (transplant) | Jul 9–Aug 6 (transplant) |
| Cauliflower | Feb 14–28 | Apr 11–25 (transplant) | Jul 9–Aug 6 (transplant) |
| Brussels sprouts | Jan 31–Feb 14 | Mar 28–Apr 11 (transplant) | Jun 25–Jul 16 (transplant) |
| Kohlrabi | Feb 28–Mar 14 | Mar 28–Apr 11 (transplant) Mar 28–Apr 11 (sow outdoors) | Aug 6–20 (sowing) |
| Bok choy / Asian greens | – | Mar 28–Apr 11 (sow outdoors) | Aug 20–Sep 3 (sowing) |
| Arugula | – | Mar 28–Apr 25 (sow outdoors) | Aug 20–Sep 17 (sowing) |
| Mustard greens | – | Mar 28–Apr 18 (sow outdoors) | Aug 20–Sep 3 (sowing) |
| Swiss chard | Mar 14–28 | Apr 11–May 2 (transplant) Apr 11–May 9 (sow outdoors) | Aug 6–20 (sowing) |
| Beet | – | Mar 28–Apr 25 (sow outdoors) | Aug 6–20 (sowing) |
| Carrot | – | Apr 4–May 2 (sow outdoors) | Jul 23–Aug 6 (sowing) |
| Radish | – | Mar 21–May 2 (sow outdoors) | Sep 3–17 (sowing) |
| Turnip | – | Mar 28–Apr 18 (sow outdoors) | Aug 6–20 (sowing) |
| Parsnip | – | Apr 4–25 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Feb 28–Mar 28 (sow outdoors) | Jul 23–Aug 6 (sowing) |
| Onion (bulbing) | Jan 31–Feb 14 | Mar 14–28 (transplant) | – |
| Green onion / scallion | – | Mar 14–Apr 11 (sow outdoors) | Aug 6–20 (sowing) |
| Leek | Jan 31–Feb 14 | Mar 28–Apr 11 (transplant) | – |
| Garlic | – | – | Sep 3–Oct 1 (sowing) |
| Shallot | – | Mar 14–28 (transplant) | Sep 3–Oct 1 (sowing) |
| Potato | – | Mar 28–Apr 11 (transplant) | Jun 25–Jul 9 (transplant) |
| Sweet potato | – | May 16–30 (transplant) | – |
| Sweet corn | – | May 2–16 (sow outdoors) | – |
| Bean, bush (snap) | – | May 2–16 (sow outdoors) | – |
| Bean, pole | – | May 2–16 (sow outdoors) | – |
| Lima bean | – | May 9–23 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 16–Jun 6 (sow outdoors) | – |
| Cucumber | Mar 28–Apr 4 | May 2–16 (transplant) May 2–16 (sow outdoors) | – |
| Summer squash / zucchini | Mar 28–Apr 4 | May 2–16 (transplant) May 2–16 (sow outdoors) | – |
| Winter squash | Mar 28–Apr 4 | May 2–16 (transplant) May 2–16 (sow outdoors) | – |
| Pumpkin | – | May 2–16 (sow outdoors) | – |
| Watermelon | Mar 28–Apr 4 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 28–Apr 4 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Okra | Mar 14–28 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Celery | Jan 31–Feb 14 | May 2–9 (transplant) | – |
| Basil | Mar 14–28 | May 2–16 (transplant) May 2–16 (sow outdoors) | – |
| Cilantro | – | Apr 11–May 9 (sow outdoors) | Aug 20–Sep 3 (sowing) |
| Parsley | Feb 14–28 | Apr 11–25 (transplant) Apr 4–25 (sow outdoors) | – |
| Dill | – | Apr 25–May 9 (sow outdoors) | Aug 20–Sep 3 (sowing) |
| Sunflower | – | Apr 25–May 9 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 28–Apr 11 (transplant) | – |
| Rhubarb (crowns) | – | Mar 28–Apr 11 (transplant) | – |
| Strawberry (plants) | – | Mar 28–Apr 11 (transplant) | Aug 6–Sep 3 (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.
Plants that do well here
Kansas has a university or garden plant program: Prairie Star Flowers. Plant frost-tender annuals after April 25 here (the average last frost). Not affiliated with the program.
Where these numbers come from
Station: Fairbury 5S, NE (NOAA GHCN-Daily ID USC00252820), elevation 1,350 ft, 10.4 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Washington, KS | 18 mi | Apr 24 | Oct 14 |
| Hebron, NE | 20 mi | Apr 24 | Oct 15 |
| Belleville, KS | 20 mi | Apr 22 | Oct 17 |
The average last-frost dates of these stations span 3 days, a rough guide to local variation. See data sources & methods.
Frost questions for 66955
When is the last frost in 66955?
The average (50% chance) last spring freeze of 32°F for ZIP 66955 is April 25. For a more cautious planting date, use May 7, when only 1 year in 10 still sees a later freeze.
When is the first frost in 66955?
The average first fall freeze is October 15. In 1 year in 10 it comes by September 30.
What hardiness zone is 66955?
ZIP 66955 is in USDA zone 6a (-10 to -5°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 66955 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
66960 Narka 68429 Reynolds 66944 Haddam 66958 Morrowville 68375 Hubbell 66959 Munden 68350 Endicott 68352 Fairbury
Other ZIP codes in Washington County
66933 66937 66943 66944 66945 66946 66953 66958 66962 66968 All Washington County frost dates · Kansas 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.