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

Planting zone for 15688 — Tarrs, PA

ZIP code 15688 (Tarrs, Westmoreland County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 1 and the first fall frost October 13.

Where ZIP 15688 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 frostMay 1
First frostOct 13
2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Tarrs, 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 Tarrs, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 1median — 50% chance of a later frost
Safe for tender plantsMay 19only 10% chance of frost after
First fall frostOctober 13median — 10% chance by Oct 3
Growing season164 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 20 and returns around October 24.

From the NOAA station Mt Pleasant, PA — 6 miles away, elevation 1,004 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 15688

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 20 – Apr 3
SpinachSow outdoors · Mar 20 – Apr 10
Broccoli, cabbageStart indoors · Feb 20 – Mar 6
Broccoli, cabbageTransplant · Apr 10 – Apr 24
Onion setsPlant outdoors · Apr 3 – Apr 17
PotatoesPlant outdoors · Apr 10 – Apr 24
LettuceSow outdoors · Apr 3 – Apr 17
Carrots, beetsSow outdoors · Apr 10 – Apr 24
TomatoesStart indoors · Mar 6 – Mar 20
TomatoesTransplant · May 8 – May 22
Peppers, eggplantStart indoors · Feb 20 – Mar 6
Peppers, eggplantTransplant · May 15 – May 29
BeansSow outdoors · May 8 – May 22
Sweet cornSow outdoors · May 8 – May 22
Cucumbers, squashSow outdoors · May 8 – May 22
Fall lettuce, spinachSow outdoors · Aug 18 – Sep 1
GarlicPlant cloves · Sep 29 – Nov 3
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 1) and first fall frost (Oct 13) 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 15688 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 Tarrs, PA.

Soil in Tarrs, PA

The soil mapped at the center of ZIP 15688 is Itmann — extremely channery loam, somewhat excessively drained.

TextureExtremely channery loama good balance for most vegetables
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter0.25%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Itmann extremely channery loam, 0 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 15688; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Tarrs, PA

Summer high82 °Faverage high, July
Winter low21 °Faverage low, January
Hot days6days a year at 90 °F or more
Freezing nights130nights a year at 32 °F or less
Growing degree days2,814base 50 °F — the season’s usable heat
Longest day15 h 02 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)
Precipitation42.7 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 37 °F, low 21 °F 37°21° JanFebruary: average high 41 °F, low 21 °F 41°21° FebMarch: average high 50 °F, low 28 °F 50°28° MarApril: average high 62 °F, low 36 °F 62°36° AprMay: average high 71 °F, low 47 °F 71°47° MayJune: average high 79 °F, low 56 °F 79°56° JunJuly: average high 82 °F, low 60 °F 82°60° JulAugust: average high 81 °F, low 59 °F 81°59° AugSeptember: average high 75 °F, low 51 °F 75°51° SepOctober: average high 64 °F, low 40 °F 64°40° OctNovember: average high 52 °F, low 31 °F 52°31° NovDecember: average high 42 °F, low 25 °F 42°25° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.09 in precipitation 3.1 JanFebruary: 2.90 in precipitation 2.9 FebMarch: 3.21 in precipitation 3.2 MarApril: 3.36 in precipitation 3.4 AprMay: 4.16 in precipitation 4.2 MayJune: 4.52 in precipitation 4.5 JunJuly: 4.47 in precipitation 4.5 JulAugust: 3.55 in precipitation 3.5 AugSeptember: 3.81 in precipitation 3.8 SepOctober: 3.11 in precipitation 3.1 OctNovember: 3.15 in precipitation 3.1 NovDecember: 3.37 in precipitation 3.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mt Pleasant, PA (6 mi away); precipitation: New Stanton 1 Sw, PA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

156396b
Hunker, PA · 2 mi
156126b
Alverton, PA · 3 mi
156796b
Ruffs Dale, PA · 4 mi
156666b
Mount Pleasant, PA · 4 mi
156976b
Youngwood, PA · 5 mi
156836b
Scottdale, PA · 5 mi
156166b
Armbrust, PA · 5 mi
156726b
New Stanton, PA · 5 mi

Pennsylvania planting zones →

Questions about 15688

What planting zone is ZIP code 15688?

ZIP code 15688 (Tarrs, 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 Tarrs, PA?

The median last spring frost (32 °F) near 15688 is May 1; after May 19 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mt Pleasant station.

When is the first frost in Tarrs, PA?

The median first fall frost near 15688 is October 13, giving a median frost-free growing season of 164 days.

When should I plant tomatoes in 15688?

Start tomato seeds indoors around Mar 6 – Mar 20 and set transplants outside around May 8 – May 22, one to three weeks after the median last frost.

How much rain and snow does 15688 get?

About 42.7 inches of precipitation a year (NOAA 1991–2020 normals, New Stanton 1 Sw station).

How hot do summers get in Tarrs, PA?

The average high peaks at 82 °F in July, with about 6 days a year at 90 °F or more.

What kind of soil does 15688 have?

The USDA soil survey maps Itmann at the center of ZIP 15688: extremely channery loam, somewhat excessively drained, pH about 4.6 (strongly acidic).

Did spring come early in Tarrs, PA in 2026?

Spring leaf-out near 15688 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 Tarrs, PA?

Long-day onions: the longest day near 15688 is 15 h 02 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 15688 change?

Yes. The 2012 USDA map put 15688 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.