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

Planting zone for Williamsport, PA

Williamsport, PA is in USDA zones 6a to 6b across its 4 ZIP codes. The median last spring frost is April 25 and the first fall frost October 24.

Williamsport on the zone map

Outlined: its 2 ZIP code areas · 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.

Zones6a–6b−10 to 0 °F
ZIP codes4
Last frostApr 25
First frostOct 24
Growing season181 days

6a 1 ZIP   6b 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Williamsport, 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 Williamsport, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 24median — 10% chance by Oct 8
Growing season181 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 10 and returns around November 4.

From the NOAA station Williamsport 2, PA, elevation 525 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 Williamsport

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12
GarlicPlant cloves · Oct 10 – Nov 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 24) 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 17703 came on Apr 1 — 4 days earlier than the 1991–2020 average (Apr 5).

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 6a in Pennsylvania

598 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 76

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 121

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 207

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 170

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 9

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Williamsport, PA.

Soil in Williamsport, PA

The soil mapped at the center of ZIP 17703 is Wet spots — silt loam, poorly drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureSilt loama good balance for most vegetables
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land.

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 17703; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Williamsport, PA

Summer high86 °Faverage high, July
Winter low21 °Faverage low, January
Hot days25days a year at 90 °F or more
Freezing nights118nights a year at 32 °F or less
Growing degree days3,226base 50 °F — the season’s usable heat
Longest day15 h 09 mindaylight on June 21
Shortest day9 h 11 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation42.7 inper year, rain and melted snow
Snowfall33 inper year; 38 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 36 °F, low 21 °F 36°21° JanFebruary: average high 39 °F, low 22 °F 39°22° FebMarch: average high 49 °F, low 29 °F 49°29° MarApril: average high 63 °F, low 39 °F 63°39° AprMay: average high 74 °F, low 50 °F 74°50° MayJune: average high 81 °F, low 59 °F 81°59° JunJuly: average high 86 °F, low 63 °F 86°63° JulAugust: average high 84 °F, low 62 °F 84°62° AugSeptember: average high 76 °F, low 55 °F 76°55° SepOctober: average high 64 °F, low 43 °F 64°43° OctNovember: average high 51 °F, low 33 °F 51°33° NovDecember: average high 40 °F, low 26 °F 40°26° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.99 in precipitation, 8.7 in snowfall 3.0❄9 JanFebruary: 2.39 in precipitation, 8.6 in snowfall 2.4❄9 FebMarch: 3.29 in precipitation, 5.7 in snowfall 3.3❄6 MarApril: 3.62 in precipitation, 0.8 in snowfall 3.6❄1 AprMay: 3.83 in precipitation 3.8 MayJune: 3.92 in precipitation 3.9 JunJuly: 4.30 in precipitation 4.3 JulAugust: 3.80 in precipitation 3.8 AugSeptember: 4.54 in precipitation 4.5 SepOctober: 3.69 in precipitation, 0.1 in snowfall 3.7 OctNovember: 3.09 in precipitation, 1.6 in snowfall 3.1❄2 NovDecember: 3.26 in precipitation, 7.1 in snowfall 3.3❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Williamsport 2, PA (within 1 mile); precipitation: Williamsport 2, PA (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Williamsport

177016a
−10 to −5 °F
177026b
−5 to 0 °F
177036b
−5 to 0 °F
177056b
−5 to 0 °F

Pennsylvania planting zones →

Questions about Williamsport

What planting zone is Williamsport, PA?

Williamsport, PA is in USDA hardiness zones 6a to 6b on the 2023 map (6a: −10 to −5 °F; 6b: −5 to 0 °F).

When is the last frost in Williamsport, PA?

The median last spring frost is April 25 and the median first fall frost is October 24 (NOAA 1991–2020 normals, Williamsport 2 station).

When can I plant a garden in Williamsport, PA?

Cool-season crops like peas and spinach go in around Mar 14 – Apr 4; tomatoes, peppers, beans and squash after about May 2, once frost risk has passed.

What kind of onions grow in Williamsport, PA?

Long-day onions: the longest day is 15 h 09 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Williamsport, PA get?

About 42.7 inches of precipitation a year and 33 inches of snowfall (NOAA 1991–2020 normals).