Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 18031 — Breinigsville, PA

ZIP code 18031 (Breinigsville, Lehigh County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 26 and the first fall frost October 14.

Where ZIP 18031 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone7a0 to 5 °F
Coldest night−17.8 to −15 °C
Last frostApr 26
First frostOct 14
2012 zone6b

Was 6b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Breinigsville, PA…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Breinigsville, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 26median — 50% chance of a later frost
Safe for tender plantsMay 13only 10% chance of frost after
First fall frostOctober 14median — 10% chance by Oct 1
Growing season171 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 10 and returns around October 26.

From the NOAA station Rodale Rsch Center, PA — 4 miles away, elevation 551 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 18031

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 15 – Mar 29
SpinachSow outdoors · Mar 15 – Apr 5
Broccoli, cabbageStart indoors · Feb 15 – Mar 1
Broccoli, cabbageTransplant · Apr 5 – Apr 19
Onion setsPlant outdoors · Mar 29 – Apr 12
PotatoesPlant outdoors · Apr 5 – Apr 19
LettuceSow outdoors · Mar 29 – Apr 12
Carrots, beetsSow outdoors · Apr 5 – Apr 19
TomatoesStart indoors · Mar 1 – Mar 15
TomatoesTransplant · May 3 – May 17
Peppers, eggplantStart indoors · Feb 15 – Mar 1
Peppers, eggplantTransplant · May 10 – May 24
BeansSow outdoors · May 3 – May 17
Sweet cornSow outdoors · May 3 – May 17
Cucumbers, squashSow outdoors · May 3 – May 17
Fall lettuce, spinachSow outdoors · Aug 19 – Sep 2
GarlicPlant cloves · Sep 30 – Nov 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Oct 14) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 18031 came on Mar 26 — 6 days earlier than the 1991–2020 average (Apr 1).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 7a in Pennsylvania

620 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Trees 78

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 123

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 212

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 181

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °FAtlantic mannagrass3 ft · blooms summer · low shade tolerance · to −8 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °F

Vines 11

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Breinigsville, PA.

Soil in Breinigsville, PA

The soil mapped at the center of ZIP 18031 is Duffield — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.7neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupBwater soaks in moderately
Farmland classprime farmlandUSDA classification

Map unit: Duffield silt loam, 3 to 8 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 18031; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Breinigsville, PA

Summer high85 °Faverage high, July
Winter low20 °Faverage low, January
Hot days15days a year at 90 °F or more
Freezing nights131nights a year at 32 °F or less
Growing degree days3,067base 50 °F — the season’s usable heat
Longest day15 h 05 mindaylight on June 21
Shortest day9 h 16 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation48.7 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 38 °F, low 20 °F 38°20° JanFebruary: average high 41 °F, low 21 °F 41°21° FebMarch: average high 49 °F, low 29 °F 49°29° MarApril: average high 62 °F, low 39 °F 62°39° AprMay: average high 72 °F, low 49 °F 72°49° MayJune: average high 80 °F, low 58 °F 80°58° JunJuly: average high 85 °F, low 62 °F 85°62° JulAugust: average high 83 °F, low 60 °F 83°60° AugSeptember: average high 77 °F, low 53 °F 77°53° SepOctober: average high 65 °F, low 41 °F 65°41° OctNovember: average high 53 °F, low 32 °F 53°32° NovDecember: average high 43 °F, low 25 °F 43°25° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.37 in precipitation 3.4 JanFebruary: 2.78 in precipitation 2.8 FebMarch: 3.93 in precipitation 3.9 MarApril: 4.10 in precipitation 4.1 AprMay: 3.77 in precipitation 3.8 MayJune: 4.48 in precipitation 4.5 JunJuly: 5.41 in precipitation 5.4 JulAugust: 4.44 in precipitation 4.4 AugSeptember: 4.78 in precipitation 4.8 SepOctober: 4.27 in precipitation 4.3 OctNovember: 3.57 in precipitation 3.6 NovDecember: 3.78 in precipitation 3.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Rodale Rsch Center, PA (4 mi away); precipitation: Rodale Rsch Center, PA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

181957a
Allentown, PA · 2 mi
180516b
Fogelsville, PA · 3 mi
180877a
Trexlertown, PA · 3 mi
195386b
Maxatawny, PA · 3 mi
181067a
Allentown, PA · 4 mi
180467a
East Texas, PA · 5 mi
195396b
Mertztown, PA · 5 mi
195627a
Topton, PA · 5 mi

Pennsylvania planting zones →

Questions about 18031

What planting zone is ZIP code 18031?

ZIP code 18031 (Breinigsville, PA) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Breinigsville, PA?

The median last spring frost (32 °F) near 18031 is April 26; after May 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Rodale Rsch Center station.

When is the first frost in Breinigsville, PA?

The median first fall frost near 18031 is October 14, giving a median frost-free growing season of 171 days.

When should I plant tomatoes in 18031?

Start tomato seeds indoors around Mar 1 – Mar 15 and set transplants outside around May 3 – May 17, one to three weeks after the median last frost.

How much rain and snow does 18031 get?

About 48.7 inches of precipitation a year (NOAA 1991–2020 normals, Rodale Rsch Center station).

How hot do summers get in Breinigsville, PA?

The average high peaks at 85 °F in July, with about 15 days a year at 90 °F or more.

What kind of soil does 18031 have?

The USDA soil survey maps Duffield at the center of ZIP 18031: silt loam, well drained, pH about 6.7 (neutral).

Did spring come early in Breinigsville, PA in 2026?

Spring leaf-out near 18031 came on Mar 26 in 2026, 6 days earlier than the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Breinigsville, PA?

Long-day onions: the longest day near 18031 is 15 h 05 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 18031 change?

Yes. The 2012 USDA map put 18031 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.