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

Planting zone for 18624 — Lake Harmony, PA

ZIP code 18624 (Lake Harmony, Carbon County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 7 and the first fall frost October 6.

Where ZIP 18624 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 7

First frostOct 6

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 Lake Harmony, 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 Lake Harmony, PA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 7median — 50% chance of a later frost

Safe for tender plantsMay 23only 10% chance of frost after

First fall frostOctober 6median — 10% chance by Sep 22

Growing season153 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 24 and returns around October 19.

From the NOAA station Francis E Walter Dam, PA — 6 miles away, elevation 1,509 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 18624

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 26 – Apr 9

SpinachSow outdoors · Mar 26 – Apr 16

Broccoli, cabbageStart indoors · Feb 26 – Mar 12

Broccoli, cabbageTransplant · Apr 16 – Apr 30

Onion setsPlant outdoors · Apr 9 – Apr 23

PotatoesPlant outdoors · Apr 16 – Apr 30

LettuceSow outdoors · Apr 9 – Apr 23

Carrots, beetsSow outdoors · Apr 16 – Apr 30

TomatoesStart indoors · Mar 12 – Mar 26

TomatoesTransplant · May 14 – May 28

Peppers, eggplantStart indoors · Feb 26 – Mar 12

Peppers, eggplantTransplant · May 21 – Jun 4

BeansSow outdoors · May 14 – May 28

Sweet cornSow outdoors · May 14 – May 28

Cucumbers, squashSow outdoors · May 14 – May 28

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 7) 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 18624 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 Lake Harmony, PA

The soil mapped at the center of ZIP 18624 is Swartswood — channery loam, well drained.

TextureChannery loama good balance for most vegetables

pH4.6strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Swartswood channery silt 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 18624; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lake Harmony, PA

Summer high79 °Faverage high, July

Winter low16 °Faverage low, January

Hot days4days a year at 90 °F or more

Freezing nights163nights a year at 32 °F or less

Growing degree days2,209base 50 °F — the season’s usable heat

Longest day15 h 08 mindaylight on June 21

Shortest day9 h 13 mindaylight on December 21

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

Precipitation48.8 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: Francis E Walter Dam, PA (6 mi away); precipitation: Francis E Walter Dam, PA (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

182106a

Albrightsville, PA · 5 mi

186616a

White Haven, PA · 5 mi

186106a

Blakeslee, PA · 6 mi

183476a

Pocono Lake, PA · 8 mi

182296b

Jim Thorpe, PA · 9 mi

186026a

Bear Creek, PA · 10 mi

183506a

Pocono Pines, PA · 10 mi

183346a

Long Pond, PA · 11 mi

Pennsylvania planting zones →

Questions about 18624

What planting zone is ZIP code 18624?

ZIP code 18624 (Lake Harmony, 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 Lake Harmony, PA?

The median last spring frost (32 °F) near 18624 is May 7; after May 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Francis E Walter Dam station.

When is the first frost in Lake Harmony, PA?

The median first fall frost near 18624 is October 6, giving a median frost-free growing season of 153 days.

When should I plant tomatoes in 18624?

Start tomato seeds indoors around Mar 12 – Mar 26 and set transplants outside around May 14 – May 28, one to three weeks after the median last frost.

How much rain and snow does 18624 get?

About 48.8 inches of precipitation a year (NOAA 1991–2020 normals, Francis E Walter Dam station).

How hot do summers get in Lake Harmony, PA?

The average high peaks at 79 °F in July, with about 4 days a year at 90 °F or more.

What kind of soil does 18624 have?

The USDA soil survey maps Swartswood at the center of ZIP 18624: channery loam, well drained, pH about 4.6 (strongly acidic).

Did spring come early in Lake Harmony, PA in 2026?

Spring leaf-out near 18624 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 Lake Harmony, PA?

Long-day onions: the longest day near 18624 is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 18624 change?

Yes. The 2012 USDA map put 18624 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.