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

Planting zone for 07856 — Mount Arlington, NJ

ZIP code 07856 (Mount Arlington, Morris County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 25 and the first fall frost October 19.

Where ZIP 07856 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 frostApr 25
First frostOct 19
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 Mount Arlington, NJ…

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 Mount Arlington, NJ

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 11only 10% chance of frost after
First fall frostOctober 19median — 10% chance by Oct 5
Growing season175 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around October 31.

From the NOAA station Andover Aeroflex Airport, NJ — 9 miles away, elevation 584 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 07856

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
Fall lettuce, spinachSow outdoors · Aug 24 – Sep 7
GarlicPlant cloves · Oct 5 – Nov 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 19) 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 07856 came on Apr 1 — 8 days earlier than the 1991–2020 average (Apr 9).

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 Mount Arlington, NJ

The soil mapped at the center of ZIP 07856 is Rockaway — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH5.0strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Rockaway sandy loam, 15 to 25 percent slopes, extremely stony.

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 07856; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mount Arlington, NJ

Summer high84 °Faverage high, July
Winter low19 °Faverage low, January
Hot days11days a year at 90 °F or more
Freezing nights127nights a year at 32 °F or less
Growing degree days2,877base 50 °F — the season’s usable heat
Longest day15 h 07 mindaylight on June 21
Shortest day9 h 14 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation51.5 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 36 °F, low 19 °F 36°19° JanFebruary: average high 39 °F, low 20 °F 39°20° FebMarch: average high 48 °F, low 28 °F 48°28° MarApril: average high 61 °F, low 38 °F 61°38° AprMay: average high 71 °F, low 48 °F 71°48° MayJune: average high 79 °F, low 57 °F 79°57° JunJuly: average high 84 °F, low 62 °F 84°62° JulAugust: average high 82 °F, low 60 °F 82°60° AugSeptember: average high 74 °F, low 52 °F 74°52° SepOctober: average high 63 °F, low 42 °F 63°42° OctNovember: average high 52 °F, low 32 °F 52°32° NovDecember: average high 41 °F, low 25 °F 41°25° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.81 in precipitation 3.8 JanFebruary: 2.97 in precipitation 3.0 FebMarch: 4.25 in precipitation 4.3 MarApril: 4.27 in precipitation 4.3 AprMay: 3.97 in precipitation 4.0 MayJune: 4.76 in precipitation 4.8 JunJuly: 4.58 in precipitation 4.6 JulAugust: 4.84 in precipitation 4.8 AugSeptember: 4.66 in precipitation 4.7 SepOctober: 5.12 in precipitation 5.1 OctNovember: 3.70 in precipitation 3.7 NovDecember: 4.52 in precipitation 4.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Andover Aeroflex Airport, NJ (9 mi away); precipitation: Mount Arlington 0.8 S, NJ (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

078856b
Wharton, NJ · 1 mi
078506b
Landing, NJ · 2 mi
078476b
Kenvil, NJ · 2 mi
078436b
Hopatcong, NJ · 2 mi
078036b
Mine Hill, NJ · 3 mi
078526b
Ledgewood, NJ · 3 mi
078496b
Lake Hopatcong, NJ · 3 mi
078016b
Dover, NJ · 3 mi

New Jersey planting zones →

Questions about 07856

What planting zone is ZIP code 07856?

ZIP code 07856 (Mount Arlington, NJ) 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 Mount Arlington, NJ?

The median last spring frost (32 °F) near 07856 is April 25; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Andover Aeroflex Airport station.

When is the first frost in Mount Arlington, NJ?

The median first fall frost near 07856 is October 19, giving a median frost-free growing season of 175 days.

When should I plant tomatoes in 07856?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 07856 get?

About 51.5 inches of precipitation a year (NOAA 1991–2020 normals, Mount Arlington 0.8 S station).

How hot do summers get in Mount Arlington, NJ?

The average high peaks at 84 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 07856 have?

The USDA soil survey maps Rockaway at the center of ZIP 07856: sandy loam, well drained, pH about 5.0 (strongly acidic).

Did spring come early in Mount Arlington, NJ in 2026?

Spring leaf-out near 07856 came on Apr 1 in 2026, 8 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mount Arlington, NJ?

Long-day onions: the longest day near 07856 is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 07856 change?

Yes. The 2012 USDA map put 07856 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.