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

Planting zone for 18977 — Washington Crossing, PA

ZIP code 18977 (Washington Crossing, Bucks County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 10 and the first fall frost November 1.

Where ZIP 18977 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.

Zone7b5 to 10 °F
Coldest night−15 to −12.2 °C
Last frostApr 10
First frostNov 1
2012 zone7a

Was 7a 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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Washington Crossing, 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 Washington Crossing, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 10median — 50% chance of a later frost
Safe for tender plantsApril 25only 10% chance of frost after
First fall frostNovember 1median — 10% chance by Oct 15
Growing season202 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 31 and returns around November 12.

From the NOAA station Trenton Mercer Co. Airport, NJ — 3 miles away, elevation 184 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 18977

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 27 – Mar 13
SpinachSow outdoors · Feb 27 – Mar 20
Broccoli, cabbageStart indoors · Jan 30 – Feb 13
Broccoli, cabbageTransplant · Mar 20 – Apr 3
Onion setsPlant outdoors · Mar 13 – Mar 27
PotatoesPlant outdoors · Mar 20 – Apr 3
LettuceSow outdoors · Mar 13 – Mar 27
Carrots, beetsSow outdoors · Mar 20 – Apr 3
TomatoesStart indoors · Feb 13 – Feb 27
TomatoesTransplant · Apr 17 – May 1
Peppers, eggplantStart indoors · Jan 30 – Feb 13
Peppers, eggplantTransplant · Apr 24 – May 8
BeansSow outdoors · Apr 17 – May 1
Sweet cornSow outdoors · Apr 17 – May 1
Cucumbers, squashSow outdoors · Apr 17 – May 1
Fall lettuce, spinachSow outdoors · Sep 6 – Sep 20
GarlicPlant cloves · Oct 18 – Nov 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 10) and first fall frost (Nov 1) 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 18977 came on Mar 22 — about the same time as the 1991–2020 average (Mar 23).

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 7b in Pennsylvania

625 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive 5 °F or colder — the bottom of zone 7b. Each links to its USDA PLANTS profile.

Trees 79

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 215

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 182

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 Washington Crossing, PA.

Soil in Washington Crossing, PA

The soil mapped at the center of ZIP 18977 is Klinesville — channery silt loam, somewhat excessively drained.

TextureChannery silt loama good balance for most vegetables
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Klinesville very channery 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 18977; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Washington Crossing, PA

Summer high86 °Faverage high, July
Winter low24 °Faverage low, January
Hot days22days a year at 90 °F or more
Freezing nights97nights a year at 32 °F or less
Growing degree days3,551base 50 °F — the season’s usable heat
Longest day15 h 03 mindaylight on June 21
Shortest day9 h 18 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation45.6 inper year, rain and melted snow
Snowfall27 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 40 °F, low 24 °F 40°24° JanFebruary: average high 43 °F, low 26 °F 43°26° FebMarch: average high 51 °F, low 33 °F 51°33° MarApril: average high 63 °F, low 42 °F 63°42° AprMay: average high 72 °F, low 52 °F 72°52° MayJune: average high 81 °F, low 61 °F 81°61° JunJuly: average high 86 °F, low 67 °F 86°67° JulAugust: average high 84 °F, low 65 °F 84°65° AugSeptember: average high 77 °F, low 58 °F 77°58° SepOctober: average high 66 °F, low 46 °F 66°46° OctNovember: average high 55 °F, low 36 °F 55°36° NovDecember: average high 44 °F, low 29 °F 44°29° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.29 in precipitation, 8.2 in snowfall 3.3❄8 JanFebruary: 2.65 in precipitation, 8.7 in snowfall 2.6❄9 FebMarch: 4.00 in precipitation, 4 in snowfall 4.0❄4 MarApril: 3.63 in precipitation, 0.5 in snowfall 3.6❄1 AprMay: 3.99 in precipitation 4.0 MayJune: 4.35 in precipitation 4.3 JunJuly: 4.42 in precipitation 4.4 JulAugust: 4.22 in precipitation 4.2 AugSeptember: 4.05 in precipitation 4.0 SepOctober: 3.79 in precipitation, 0.1 in snowfall 3.8 OctNovember: 3.20 in precipitation, 0.5 in snowfall 3.2❄1 NovDecember: 4.04 in precipitation, 4.6 in snowfall 4.0❄5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Trenton Mercer Co. Airport, NJ (3 mi away); precipitation: Trenton Mercer Co. Airport, NJ (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

085607a
Titusville, NJ · 2 mi
086287b
Trenton, NJ · 3 mi
189407a
Newtown, PA · 4 mi
190677a
Morrisville, PA · 4 mi
086187b
Trenton, NJ · 5 mi
085347a
Pennington, NJ · 5 mi
086387a
Trenton, NJ · 6 mi
085307a
Lambertville, NJ · 6 mi

Pennsylvania planting zones →

Questions about 18977

What planting zone is ZIP code 18977?

ZIP code 18977 (Washington Crossing, PA) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Washington Crossing, PA?

The median last spring frost (32 °F) near 18977 is April 10; after April 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Trenton Mercer Co. Airport station.

When is the first frost in Washington Crossing, PA?

The median first fall frost near 18977 is November 1, giving a median frost-free growing season of 202 days.

When should I plant tomatoes in 18977?

Start tomato seeds indoors around Feb 13 – Feb 27 and set transplants outside around Apr 17 – May 1, one to three weeks after the median last frost.

How much rain and snow does 18977 get?

About 45.6 inches of precipitation a year and 27 inches of snowfall (NOAA 1991–2020 normals, Trenton Mercer Co. Airport station).

How hot do summers get in Washington Crossing, PA?

The average high peaks at 86 °F in July, with about 22 days a year at 90 °F or more.

What kind of soil does 18977 have?

The USDA soil survey maps Klinesville at the center of ZIP 18977: channery silt loam, somewhat excessively drained, pH about 6.1 (slightly acidic).

Did spring come early in Washington Crossing, PA in 2026?

Spring leaf-out near 18977 came on Mar 22 in 2026, about the same as the 1991–2020 average (Mar 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Washington Crossing, PA?

Long-day onions: the longest day near 18977 is 15 h 03 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 18977 change?

Yes. The 2012 USDA map put 18977 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.