Fall in zone 6bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 18051 (Lehigh County, PA)
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, Rodale Rsch Ctr, PA (4 miles away).
- Average last spring frostApr 2650% chance of a 32°F freeze after this date
- Average first fall frostOct 1450% chance of a 32°F freeze by this date
- Growing season (frost-free)171 daysmedian, 32°F threshold
- USDA hardiness zone6b-5 to 0°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 18051, 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
59°F 55°F or warmer
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 Avondale 2 N (51 mi), Mahantango Ck (53 mi).
4-inch depth
61°F 55°F or warmer
24-hour average · latest 57°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Avondale 2 N (51 mi), Mahantango Ck (53 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 18051 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 61°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent (annual bluegrass, winter weeds): window open as soil cools through the 70s and 60s.
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 10 |
| 50% (the "average" last frost) | Apr 26 |
| 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) | Oct 1 |
| 50% (the "average" first frost) | Oct 14 |
| 90% (late: most years have frozen by now) | Oct 31 |
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 5 |
| 32°F (freeze) | Apr 26 | Oct 14 |
| 28°F (hard freeze) | Apr 10 | Oct 26 |
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 18051
Dates count from your average last spring frost (Apr 26) and first fall frost (Oct 14). 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 1–15 | May 3–17 (transplant) | – |
| Pepper (sweet and hot) | Feb 15–Mar 1 | May 10–24 (transplant) | – |
| Eggplant | Feb 15–Mar 1 | May 10–24 (transplant) | – |
| Tomatillo | Mar 1–15 | May 3–17 (transplant) | – |
| Lettuce | Mar 1–15 | Apr 5–26 (transplant) Mar 29–May 10 (sow outdoors) | Aug 19–Sep 9 (transplant) Aug 5–Sep 2 (sowing) |
| Spinach | – | Mar 15–Apr 5 (sow outdoors) | Aug 19–Sep 9 (sowing) |
| Kale | Mar 1–15 | Mar 29–Apr 12 (transplant) Mar 29–Apr 12 (sow outdoors) | Jul 22–Aug 19 (transplant) Jul 8–Aug 5 (sowing) |
| Collards | Mar 1–15 | Mar 29–Apr 26 (transplant) Mar 29–Apr 26 (sow outdoors) | Jul 22–Aug 19 (transplant) Jul 8–Aug 5 (sowing) |
| Broccoli | Feb 15–Mar 1 | Mar 29–Apr 12 (transplant) | Jul 8–Aug 5 (transplant) |
| Cabbage | Feb 15–Mar 1 | Mar 29–Apr 12 (transplant) | Jul 8–Aug 5 (transplant) |
| Cauliflower | Feb 15–Mar 1 | Apr 12–26 (transplant) | Jul 8–Aug 5 (transplant) |
| Brussels sprouts | Feb 1–15 | Mar 29–Apr 12 (transplant) | Jun 24–Jul 15 (transplant) |
| Kohlrabi | Mar 1–15 | Mar 29–Apr 12 (transplant) Mar 29–Apr 12 (sow outdoors) | Aug 5–19 (sowing) |
| Bok choy / Asian greens | – | Mar 29–Apr 12 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Arugula | – | Mar 29–Apr 26 (sow outdoors) | Aug 19–Sep 16 (sowing) |
| Mustard greens | – | Mar 29–Apr 19 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Swiss chard | Mar 15–29 | Apr 12–May 3 (transplant) Apr 12–May 10 (sow outdoors) | Aug 5–19 (sowing) |
| Beet | – | Mar 29–Apr 26 (sow outdoors) | Aug 5–19 (sowing) |
| Carrot | – | Apr 5–May 3 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Radish | – | Mar 22–May 3 (sow outdoors) | Sep 2–16 (sowing) |
| Turnip | – | Mar 29–Apr 19 (sow outdoors) | Aug 5–19 (sowing) |
| Parsnip | – | Apr 5–26 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 1–29 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Onion (bulbing) | Feb 1–15 | Mar 15–29 (transplant) | – |
| Green onion / scallion | – | Mar 15–Apr 12 (sow outdoors) | Aug 5–19 (sowing) |
| Leek | Feb 1–15 | Mar 29–Apr 12 (transplant) | – |
| Garlic | – | – | Sep 2–30 (sowing) |
| Shallot | – | Mar 15–29 (transplant) | Sep 2–30 (sowing) |
| Potato | – | Mar 29–Apr 12 (transplant) | Jun 24–Jul 8 (transplant) |
| Sweet potato | – | May 17–31 (transplant) | – |
| Sweet corn | – | May 3–17 (sow outdoors) | – |
| Bean, bush (snap) | – | May 3–17 (sow outdoors) | – |
| Bean, pole | – | May 3–17 (sow outdoors) | – |
| Lima bean | – | May 10–24 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 17–Jun 7 (sow outdoors) | – |
| Cucumber | Mar 29–Apr 5 | May 3–17 (transplant) May 3–17 (sow outdoors) | – |
| Summer squash / zucchini | Mar 29–Apr 5 | May 3–17 (transplant) May 3–17 (sow outdoors) | – |
| Winter squash | Mar 29–Apr 5 | May 3–17 (transplant) May 3–17 (sow outdoors) | – |
| Pumpkin | – | May 3–17 (sow outdoors) | – |
| Watermelon | Mar 29–Apr 5 | May 10–24 (transplant) May 10–24 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 29–Apr 5 | May 10–24 (transplant) May 10–24 (sow outdoors) | – |
| Okra | Mar 15–29 | May 10–24 (transplant) May 10–24 (sow outdoors) | – |
| Celery | Feb 1–15 | May 3–10 (transplant) | – |
| Basil | Mar 15–29 | May 3–17 (transplant) May 3–17 (sow outdoors) | – |
| Cilantro | – | Apr 12–May 10 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Parsley | Feb 15–Mar 1 | Apr 12–26 (transplant) Apr 5–26 (sow outdoors) | – |
| Dill | – | Apr 26–May 10 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Sunflower | – | Apr 26–May 10 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 29–Apr 12 (transplant) | – |
| Rhubarb (crowns) | – | Mar 29–Apr 12 (transplant) | – |
| Strawberry (plants) | – | Mar 29–Apr 12 (transplant) | Aug 5–Sep 2 (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: Rodale Rsch Ctr, PA (NOAA GHCN-Daily ID USC00367578), elevation 550 ft, 4.2 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Allentown Intl AP, PA | 12 mi | Apr 20 | Oct 24 |
| Lehighton 1SSW, PA | 16 mi | Apr 21 | Oct 23 |
| Hamburg, PA | 17 mi | Apr 16 | Oct 25 |
The average last-frost dates of these stations span 10 days, a rough guide to local variation. See data sources & methods.
Frost questions for 18051
When is the last frost in 18051?
The average (50% chance) last spring freeze of 32°F for ZIP 18051 is April 26. 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 18051?
The average first fall freeze is October 14. In 1 year in 10 it comes by October 1.
What hardiness zone is 18051?
ZIP 18051 is in USDA zone 6b (-5 to 0°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 18051 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
18195 18031 Breinigsville 18069 19538 Maxatawny 18087 Trexlertown 18078 Schnecksville 18106 Wescosville 18066 New Tripoli
Other ZIP codes in Lehigh County
18018 18031 18032 18034 18036 18037 18046 18049 18052 18053 18059 18062 18065 18066 18069 18078 18079 18080 18087 18092 18101 18102 18103 18104 All Lehigh County frost dates · Pennsylvania 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.