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

Planting zone for 16421 — Harborcreek, PA

ZIP code 16421 (Harborcreek, Erie County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 26 and the first fall frost November 4.

Where ZIP 16421 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 26
First frostNov 4
2012 zone6b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Harborcreek, 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 Harborcreek, 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 frostNovember 4median — 10% chance by Oct 21
Growing season192 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around November 16.

From the NOAA station Erie Intl Airport, PA — 14 miles away, elevation 732 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 16421

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 · Sep 9 – Sep 23
GarlicPlant cloves · Oct 21 – Nov 25
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Nov 4) 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 16421 came on Mar 26 — 12 days earlier than the 1991–2020 average (Apr 7).

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 6b in Pennsylvania

605 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 6b. 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 122

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 209

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 173

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 10

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 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °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 Harborcreek, PA.

Soil in Harborcreek, PA

The soil mapped at the center of ZIP 16421 is Volusia — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables
pH6.0slightly acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter5%high
Hydrologic groupDwater soaks in very slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Volusia-Fremont silt loams, 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 16421; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Harborcreek, PA

Summer high81 °Faverage high, July
Winter low21 °Faverage low, January
Hot days5days a year at 90 °F or more
Freezing nights111nights a year at 32 °F or less
Growing degree days3,010base 50 °F — the season’s usable heat
Longest day15 h 16 mindaylight on June 21
Shortest day9 h 06 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation43.4 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 35 °F, low 21 °F 35°21° JanFebruary: average high 37 °F, low 21 °F 37°21° FebMarch: average high 44 °F, low 28 °F 44°28° MarApril: average high 57 °F, low 38 °F 57°38° AprMay: average high 68 °F, low 49 °F 68°49° MayJune: average high 77 °F, low 59 °F 77°59° JunJuly: average high 81 °F, low 64 °F 81°64° JulAugust: average high 80 °F, low 63 °F 80°63° AugSeptember: average high 74 °F, low 57 °F 74°57° SepOctober: average high 62 °F, low 46 °F 62°46° OctNovember: average high 51 °F, low 37 °F 51°37° NovDecember: average high 40 °F, low 28 °F 40°28° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.63 in precipitation 2.6 JanFebruary: 2.18 in precipitation 2.2 FebMarch: 2.82 in precipitation 2.8 MarApril: 3.72 in precipitation 3.7 AprMay: 3.86 in precipitation 3.9 MayJune: 3.97 in precipitation 4.0 JunJuly: 4.10 in precipitation 4.1 JulAugust: 3.58 in precipitation 3.6 AugSeptember: 4.60 in precipitation 4.6 SepOctober: 4.51 in precipitation 4.5 OctNovember: 3.86 in precipitation 3.9 NovDecember: 3.57 in precipitation 3.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Erie Intl Airport, PA (14 mi away); precipitation: North East 1.2 Wnw, PA (6 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.

165117a
Erie, PA · 3 mi
165106b
Erie, PA · 4 mi
165636b
Erie, PA · 4 mi
164286a
North East, PA · 6 mi
165146b
Erie, PA · 6 mi
165156b
Erie, PA · 6 mi
165317a
Erie, PA · 6 mi
165446b
Erie, PA · 6 mi

Pennsylvania planting zones →

Questions about 16421

What planting zone is ZIP code 16421?

ZIP code 16421 (Harborcreek, PA) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Harborcreek, PA?

The median last spring frost (32 °F) near 16421 is April 26; after May 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Erie Intl Airport station.

When is the first frost in Harborcreek, PA?

The median first fall frost near 16421 is November 4, giving a median frost-free growing season of 192 days.

When should I plant tomatoes in 16421?

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 16421 get?

About 43.4 inches of precipitation a year (NOAA 1991–2020 normals, North East 1.2 Wnw station).

How hot do summers get in Harborcreek, PA?

The average high peaks at 81 °F in July, with about 5 days a year at 90 °F or more.

What kind of soil does 16421 have?

The USDA soil survey maps Volusia at the center of ZIP 16421: silt loam, somewhat poorly drained, pH about 6.0 (slightly acidic).

Did spring come early in Harborcreek, PA in 2026?

Spring leaf-out near 16421 came on Mar 26 in 2026, 12 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Harborcreek, PA?

Long-day onions: the longest day near 16421 is 15 h 16 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).