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

Planting zone for 18616 — Forksville, PA

ZIP code 18616 (Forksville, Sullivan County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 6 and the first fall frost October 7.

Where ZIP 18616 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 6

First frostOct 7

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Forksville, 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 Forksville, PA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 6median — 50% chance of a later frost

Safe for tender plantsMay 22only 10% chance of frost after

First fall frostOctober 7median — 10% chance by Sep 24

Growing season154 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 20.

From the NOAA station Laporte, PA — 10 miles away, elevation 1,965 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 18616

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 25 – Apr 8

SpinachSow outdoors · Mar 25 – Apr 15

Broccoli, cabbageStart indoors · Feb 25 – Mar 11

Broccoli, cabbageTransplant · Apr 15 – Apr 29

Onion setsPlant outdoors · Apr 8 – Apr 22

PotatoesPlant outdoors · Apr 15 – Apr 29

LettuceSow outdoors · Apr 8 – Apr 22

Carrots, beetsSow outdoors · Apr 15 – Apr 29

TomatoesStart indoors · Mar 11 – Mar 25

TomatoesTransplant · May 13 – May 27

Peppers, eggplantStart indoors · Feb 25 – Mar 11

Peppers, eggplantTransplant · May 20 – Jun 3

BeansSow outdoors · May 13 – May 27

Sweet cornSow outdoors · May 13 – May 27

Cucumbers, squashSow outdoors · May 13 – May 27

Fall lettuce, spinachSow outdoors · Aug 12 – Aug 26

GarlicPlant cloves · Sep 23 – Oct 28

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 6) and first fall frost (Oct 7) 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 18616 came on Apr 5 — 8 days earlier than the 1991–2020 average (Apr 13).

average
Apr 132026
Apr 5

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).

Soil in Forksville, PA

The soil mapped at the center of ZIP 18616 is Wellsboro — channery silt loam, moderately well drained.

TextureChannery silt loama good balance for most vegetables

pH5.5moderately acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter5%high

Hydrologic groupDwater soaks in very slowly

Farmland classprime farmlandUSDA classification

Map unit: Wellsboro channery 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 18616; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Forksville, PA

Summer high78 °Faverage high, July

Winter low14 °Faverage low, January

Hot days1days a year at 90 °F or more

Freezing nights149nights a year at 32 °F or less

Growing degree days2,033base 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)

Precipitation53.3 inper year, rain and melted snow

Snowfall70 inper year; 82 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Laporte, PA (10 mi away); precipitation: Laporte, PA (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

177686a

Shunk, PA · 7 mi

177316a

Eagles Mere, PA · 7 mi

186196a

Hillsgrove, PA · 7 mi

188336a

New Albany, PA · 10 mi

188326a

Monroeton, PA · 12 mi

Muncy Valley, PA · 13 mi

Pennsylvania planting zones →

Questions about 18616

What planting zone is ZIP code 18616?

ZIP code 18616 (Forksville, 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 Forksville, PA?

The median last spring frost (32 °F) near 18616 is May 6; after May 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Laporte station.

When is the first frost in Forksville, PA?

The median first fall frost near 18616 is October 7, giving a median frost-free growing season of 154 days.

When should I plant tomatoes in 18616?

Start tomato seeds indoors around Mar 11 – Mar 25 and set transplants outside around May 13 – May 27, one to three weeks after the median last frost.

How much rain and snow does 18616 get?

About 53.3 inches of precipitation a year and 70 inches of snowfall (NOAA 1991–2020 normals, Laporte station).

How hot do summers get in Forksville, PA?

The average high peaks at 78 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 18616 have?

The USDA soil survey maps Wellsboro at the center of ZIP 18616: channery silt loam, moderately well drained, pH about 5.5 (moderately acidic).

Did spring come early in Forksville, PA in 2026?

Spring leaf-out near 18616 came on Apr 5 in 2026, 8 days earlier than the 1991–2020 average (Apr 13), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Forksville, PA?

Long-day onions: the longest day near 18616 is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).