Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 16255 — Sligo, PA

ZIP code 16255 (Sligo, Clarion County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 9 and the first fall frost October 11.

Where ZIP 16255 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostMay 9

First frostOct 11

2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Sligo, 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 Sligo, PA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 9median — 50% chance of a later frost

Safe for tender plantsMay 24only 10% chance of frost after

First fall frostOctober 11median — 10% chance by Sep 30

Growing season154 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 29 and returns around October 24.

From the NOAA station Clarion 3 Sw, PA — 5 miles away, elevation 1,040 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 16255

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 28 – Apr 11

SpinachSow outdoors · Mar 28 – Apr 18

Broccoli, cabbageStart indoors · Feb 28 – Mar 14

Broccoli, cabbageTransplant · Apr 18 – May 2

Onion setsPlant outdoors · Apr 11 – Apr 25

PotatoesPlant outdoors · Apr 18 – May 2

LettuceSow outdoors · Apr 11 – Apr 25

Carrots, beetsSow outdoors · Apr 18 – May 2

TomatoesStart indoors · Mar 14 – Mar 28

TomatoesTransplant · May 16 – May 30

Peppers, eggplantStart indoors · Feb 28 – Mar 14

Peppers, eggplantTransplant · May 23 – Jun 6

BeansSow outdoors · May 16 – May 30

Sweet cornSow outdoors · May 16 – May 30

Cucumbers, squashSow outdoors · May 16 – May 30

Fall lettuce, spinachSow outdoors · Aug 16 – Aug 30

GarlicPlant cloves · Sep 27 – Nov 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 9) and first fall frost (Oct 11) 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 16255 came on Mar 21 — 18 days earlier than the 1991–2020 average (Apr 8).

average
Apr 82026
Mar 21

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.

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 Sligo, PA.

Soil in Sligo, PA

The soil mapped at the center of ZIP 16255 is Bethesda — channery silt loam, well drained.

TextureChannery silt loama good balance for most vegetables

pH5.2strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.1%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Bethesda-Fairpoint channery silt loams, 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 16255; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sligo, PA

Summer high82 °Faverage high, July

Winter low16 °Faverage low, January

Hot days9days a year at 90 °F or more

Freezing nights155nights a year at 32 °F or less

Growing degree days2,453base 50 °F — the season’s usable heat

Longest day15 h 08 mindaylight on June 21

Shortest day9 h 12 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation46.9 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Clarion 3 Sw, PA (5 mi away); precipitation: Clarion 3 Sw, PA (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

162136a

Callensburg, PA · 5 mi

162216a

Curllsville, PA · 5 mi

162486a

Rimersburg, PA · 7 mi

Turkey City, PA · 9 mi

162546a

Shippenville, PA · 9 mi

162246a

Fairmount City, PA · 10 mi

Pennsylvania planting zones →

Questions about 16255

What planting zone is ZIP code 16255?

ZIP code 16255 (Sligo, PA) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Sligo, PA?

The median last spring frost (32 °F) near 16255 is May 9; after May 24 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Clarion 3 Sw station.

When is the first frost in Sligo, PA?

The median first fall frost near 16255 is October 11, giving a median frost-free growing season of 154 days.

When should I plant tomatoes in 16255?

Start tomato seeds indoors around Mar 14 – Mar 28 and set transplants outside around May 16 – May 30, one to three weeks after the median last frost.

How much rain and snow does 16255 get?

About 46.9 inches of precipitation a year (NOAA 1991–2020 normals, Clarion 3 Sw station).

How hot do summers get in Sligo, PA?

The average high peaks at 82 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 16255 have?

The USDA soil survey maps Bethesda at the center of ZIP 16255: channery silt loam, well drained, pH about 5.2 (strongly acidic).

Did spring come early in Sligo, PA in 2026?

Spring leaf-out near 16255 came on Mar 21 in 2026, 18 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sligo, PA?

Long-day onions: the longest day near 16255 is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 16255 change?

Yes. The 2012 USDA map put 16255 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.