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

Planting zone for 15857 — Saint Marys, PA

ZIP code 15857 (Saint Marys, Elk County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 14 and the first fall frost October 6.

Where ZIP 15857 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostMay 14
First frostOct 6
2012 zone5a

Was 5a 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Saint Marys, 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 Saint Marys, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 14median — 50% chance of a later frost
Safe for tender plantsMay 29only 10% chance of frost after
First fall frostOctober 6median — 10% chance by Sep 24
Growing season143 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 3 and returns around October 18.

From the NOAA station Glen Hazel 2 Ne Dam, PA — 8 miles away, elevation 1,719 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 15857

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 2 – Apr 16
SpinachSow outdoors · Apr 2 – Apr 23
Broccoli, cabbageStart indoors · Mar 5 – Mar 19
Broccoli, cabbageTransplant · Apr 23 – May 7
Onion setsPlant outdoors · Apr 16 – Apr 30
PotatoesPlant outdoors · Apr 23 – May 7
LettuceSow outdoors · Apr 16 – Apr 30
Carrots, beetsSow outdoors · Apr 23 – May 7
TomatoesStart indoors · Mar 19 – Apr 2
TomatoesTransplant · May 21 – Jun 4
Peppers, eggplantStart indoors · Mar 5 – Mar 19
Peppers, eggplantTransplant · May 28 – Jun 11
BeansSow outdoors · May 21 – Jun 4
Sweet cornSow outdoors · May 21 – Jun 4
Cucumbers, squashSow outdoors · May 21 – Jun 4
Fall lettuce, spinachSow outdoors · Aug 11 – Aug 25
GarlicPlant cloves · Sep 22 – Oct 27
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 14) and first fall frost (Oct 6) 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 15857 came on Apr 4 — 8 days earlier than the 1991–2020 average (Apr 12).

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 5b in Pennsylvania

572 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 75

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 113

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 198

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 166

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 8

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 honeysuckle16 ft · blooms late summer · low 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 Saint Marys, PA.

Soil in Saint Marys, PA

The soil mapped at the center of ZIP 15857 is Wharton — slightly decomposed plant material, moderately well drained.

TextureSlightly decomposed plant materialtop layer
pH5.0strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter69%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Wharton silt loam, 15 to 25 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 15857; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Marys, PA

Summer high79 °Faverage high, July
Winter low13 °Faverage low, January
Hot days1days a year at 90 °F or more
Freezing nights163nights a year at 32 °F or less
Growing degree days2,008base 50 °F — the season’s usable heat
Longest day15 h 11 mindaylight on June 21
Shortest day9 h 10 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation45 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 31 °F, low 13 °F 31°13° JanFebruary: average high 33 °F, low 14 °F 33°14° FebMarch: average high 43 °F, low 21 °F 43°21° MarApril: average high 56 °F, low 31 °F 56°31° AprMay: average high 67 °F, low 42 °F 67°42° MayJune: average high 75 °F, low 51 °F 75°51° JunJuly: average high 79 °F, low 55 °F 79°55° JulAugust: average high 77 °F, low 54 °F 77°54° AugSeptember: average high 71 °F, low 48 °F 71°48° SepOctober: average high 59 °F, low 37 °F 59°37° OctNovember: average high 46 °F, low 28 °F 46°28° NovDecember: average high 35 °F, low 20 °F 35°20° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.56 in precipitation 3.6 JanFebruary: 2.47 in precipitation 2.5 FebMarch: 3.49 in precipitation 3.5 MarApril: 3.92 in precipitation 3.9 AprMay: 4.17 in precipitation 4.2 MayJune: 4.34 in precipitation 4.3 JunJuly: 3.94 in precipitation 3.9 JulAugust: 3.89 in precipitation 3.9 AugSeptember: 4.40 in precipitation 4.4 SepOctober: 3.58 in precipitation 3.6 OctNovember: 3.74 in precipitation 3.7 NovDecember: 3.47 in precipitation 3.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Glen Hazel 2 Ne Dam, PA (8 mi away); precipitation: St. Marys 1.7 Se, PA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

167285b
De Young, PA · 8 mi
158315b
Dagus Mines, PA · 8 mi
158216a
Benezett, PA · 9 mi
158465b
Kersey, PA · 9 mi
158705b
Wilcox, PA · 9 mi
158455b
Johnsonburg, PA · 10 mi
158345b
Emporium, PA · 11 mi
158686a
Weedville, PA · 12 mi

Pennsylvania planting zones →

Questions about 15857

What planting zone is ZIP code 15857?

ZIP code 15857 (Saint Marys, PA) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Saint Marys, PA?

The median last spring frost (32 °F) near 15857 is May 14; after May 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Glen Hazel 2 Ne Dam station.

When is the first frost in Saint Marys, PA?

The median first fall frost near 15857 is October 6, giving a median frost-free growing season of 143 days.

When should I plant tomatoes in 15857?

Start tomato seeds indoors around Mar 19 – Apr 2 and set transplants outside around May 21 – Jun 4, one to three weeks after the median last frost.

How much rain and snow does 15857 get?

About 45 inches of precipitation a year (NOAA 1991–2020 normals, St. Marys 1.7 Se station).

How hot do summers get in Saint Marys, PA?

The average high peaks at 79 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 15857 have?

The USDA soil survey maps Wharton at the center of ZIP 15857: slightly decomposed plant material, moderately well drained, pH about 5.0 (strongly acidic).

Did spring come early in Saint Marys, PA in 2026?

Spring leaf-out near 15857 came on Apr 4 in 2026, 8 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint Marys, PA?

Long-day onions: the longest day near 15857 is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 15857 change?

Yes. The 2012 USDA map put 15857 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.