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

Planting zone for 15108 — Coraopolis, PA

ZIP code 15108 (Coraopolis, Allegheny County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 23 and the first fall frost October 23.

Where ZIP 15108 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 23
First frostOct 23
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 Coraopolis, 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 Coraopolis, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 23median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 23median — 10% chance by Oct 9
Growing season181 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around November 4.

From the NOAA station Pittsburgh Intl Airport, PA — within 1 mile, elevation 1,204 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 15108

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 12 – Mar 26
SpinachSow outdoors · Mar 12 – Apr 2
Broccoli, cabbageStart indoors · Feb 12 – Feb 26
Broccoli, cabbageTransplant · Apr 2 – Apr 16
Onion setsPlant outdoors · Mar 26 – Apr 9
PotatoesPlant outdoors · Apr 2 – Apr 16
LettuceSow outdoors · Mar 26 – Apr 9
Carrots, beetsSow outdoors · Apr 2 – Apr 16
TomatoesStart indoors · Feb 26 – Mar 12
TomatoesTransplant · Apr 30 – May 14
Peppers, eggplantStart indoors · Feb 12 – Feb 26
Peppers, eggplantTransplant · May 7 – May 21
BeansSow outdoors · Apr 30 – May 14
Sweet cornSow outdoors · Apr 30 – May 14
Cucumbers, squashSow outdoors · Apr 30 – May 14
Fall lettuce, spinachSow outdoors · Aug 28 – Sep 11
GarlicPlant cloves · Oct 9 – Nov 13
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 23) 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 15108 came on Mar 10 — 17 days earlier than the 1991–2020 average (Mar 27).

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 Coraopolis, PA.

Soil in Coraopolis, PA

The soil mapped at the center of ZIP 15108 is Dormont — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter2.6%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classprime farmlandUSDA classification

Map unit: Dormont 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 15108; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Coraopolis, PA

Summer high83 °Faverage high, July
Winter low21 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights114nights a year at 32 °F or less
Growing degree days3,191base 50 °F — the season’s usable heat
Longest day15 h 04 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)
Precipitation39.6 inper year, rain and melted snow
Snowfall44 inper year; 40 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 36 °F, low 21 °F 36°21° JanFebruary: average high 40 °F, low 23 °F 40°23° FebMarch: average high 49 °F, low 30 °F 49°30° MarApril: average high 62 °F, low 41 °F 62°41° AprMay: average high 72 °F, low 51 °F 72°51° MayJune: average high 79 °F, low 59 °F 79°59° JunJuly: average high 83 °F, low 63 °F 83°63° JulAugust: average high 82 °F, low 62 °F 82°62° AugSeptember: average high 75 °F, low 55 °F 75°55° SepOctober: average high 63 °F, low 44 °F 63°44° OctNovember: average high 51 °F, low 34 °F 51°34° NovDecember: average high 41 °F, low 27 °F 41°27° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.96 in precipitation, 13.3 in snowfall 3.0❄13 JanFebruary: 2.62 in precipitation, 11.7 in snowfall 2.6❄12 FebMarch: 3.15 in precipitation, 7.6 in snowfall 3.1❄8 MarApril: 3.32 in precipitation, 1 in snowfall 3.3❄1 AprMay: 3.83 in precipitation 3.8 MayJune: 4.12 in precipitation 4.1 JunJuly: 4.26 in precipitation 4.3 JulAugust: 3.52 in precipitation 3.5 AugSeptember: 3.30 in precipitation 3.3 SepOctober: 2.83 in precipitation, 0.4 in snowfall 2.8 OctNovember: 2.86 in precipitation, 2.4 in snowfall 2.9❄2 NovDecember: 2.84 in precipitation, 7.7 in snowfall 2.8❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Pittsburgh Intl Airport, PA (within 1 mile); precipitation: Pittsburgh Intl Airport, PA (within 1 mile). 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.

150467a
Crescent, PA · 4 mi
150567a
Leetsdale, PA · 4 mi
152257a
Pittsburgh, PA · 5 mi
151266b
Imperial, PA · 5 mi
150816b
South Heights, PA · 5 mi
151436b
Sewickley, PA · 5 mi
151366b
Mc Kees Rocks, PA · 6 mi
150716b
Oakdale, PA · 6 mi

Pennsylvania planting zones →

Questions about 15108

What planting zone is ZIP code 15108?

ZIP code 15108 (Coraopolis, 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 Coraopolis, PA?

The median last spring frost (32 °F) near 15108 is April 23; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Pittsburgh Intl Airport station.

When is the first frost in Coraopolis, PA?

The median first fall frost near 15108 is October 23, giving a median frost-free growing season of 181 days.

When should I plant tomatoes in 15108?

Start tomato seeds indoors around Feb 26 – Mar 12 and set transplants outside around Apr 30 – May 14, one to three weeks after the median last frost.

How much rain and snow does 15108 get?

About 39.6 inches of precipitation a year and 44 inches of snowfall (NOAA 1991–2020 normals, Pittsburgh Intl Airport station).

How hot do summers get in Coraopolis, PA?

The average high peaks at 83 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 15108 have?

The USDA soil survey maps Dormont at the center of ZIP 15108: silt loam, moderately well drained, pH about 6.2 (slightly acidic).

Did spring come early in Coraopolis, PA in 2026?

Spring leaf-out near 15108 came on Mar 10 in 2026, 17 days earlier than the 1991–2020 average (Mar 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Coraopolis, PA?

Long-day onions: the longest day near 15108 is 15 h 04 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).