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

Planting zone for 03576 — Colebrook, NH

ZIP code 03576 (Colebrook, Coos County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 31 and the first fall frost September 21.

Where ZIP 03576 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.

Zone4a−30 to −25 °F

Coldest night−34.4 to −31.7 °C

Last frostMay 31

First frostSep 21

2012 zone4a

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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Colebrook, NH…

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 Colebrook, NH

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 31median — 50% chance of a later frost

Safe for tender plantsJune 14only 10% chance of frost after

First fall frostSeptember 21median — 10% chance by Sep 7

Growing season112 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 17 and returns around October 1.

From the NOAA station Colebrook 3sw, NH — 8 miles away, elevation 1,119 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 03576

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 19 – May 3

SpinachSow outdoors · Apr 19 – May 10

Broccoli, cabbageStart indoors · Mar 22 – Apr 5

Broccoli, cabbageTransplant · May 10 – May 24

Onion setsPlant outdoors · May 3 – May 17

PotatoesPlant outdoors · May 10 – May 24

LettuceSow outdoors · May 3 – May 17

Carrots, beetsSow outdoors · May 10 – May 24

TomatoesStart indoors · Apr 5 – Apr 19

TomatoesTransplant · Jun 7 – Jun 21

Peppers, eggplantStart indoors · Mar 22 – Apr 5

Peppers, eggplantTransplant · Jun 14 – Jun 28

BeansSow outdoors · Jun 7 – Jun 21

Sweet cornSow outdoors · Jun 7 – Jun 21

Cucumbers, squashSow outdoors · Jun 7 – Jun 21

Fall lettuce, spinachSow outdoors · Jul 27 – Aug 10

GarlicPlant cloves · Sep 7 – Oct 12

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 31) and first fall frost (Sep 21) 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 03576 came on Apr 23 — 11 days earlier than the 1991–2020 average (May 4).

average
May 42026
Apr 23

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 4a in New Hampshire

379 plants native to the lower 48 states, recorded in New Hampshire, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. 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 Colebrook, NH.

Soil in Colebrook, NH

The soil mapped at the center of ZIP 03576 is Tunbridge — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH5.4strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter4%moderate

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of local importanceUSDA classification

Map unit: Tunbridge-Plaisted-Lyman complex, 8 to 15 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 03576; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Colebrook, NH

Summer high77 °Faverage high, July

Winter low0 °Faverage low, January

Hot days1days a year at 90 °F or more

Freezing nights191nights a year at 32 °F or less

Growing degree days1,527base 50 °F — the season’s usable heat

Longest day15 h 36 mindaylight on June 21

Shortest day8 h 47 mindaylight on December 21

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

Precipitation41.3 inper year, rain and melted snow

Snowfall81 inper year; 119 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: Colebrook 3sw, NH (8 mi away); precipitation: Colebrook 3sw, NH (8 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.

059024a

Beecher Falls, VT · 9 mi

035974a

West Stewartstown, NH · 10 mi

Mount Washington, NH · 14 mi

035904a

North Stratford, NH · 15 mi

035924a

Pittsburg, NH · 16 mi

035794b

Errol, NH · 17 mi

New Hampshire planting zones →

Questions about 03576

What planting zone is ZIP code 03576?

ZIP code 03576 (Colebrook, NH) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Colebrook, NH?

The median last spring frost (32 °F) near 03576 is May 31; after June 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Colebrook 3sw station.

When is the first frost in Colebrook, NH?

The median first fall frost near 03576 is September 21, giving a median frost-free growing season of 112 days.

When should I plant tomatoes in 03576?

Start tomato seeds indoors around Apr 5 – Apr 19 and set transplants outside around Jun 7 – Jun 21, one to three weeks after the median last frost.

How much rain and snow does 03576 get?

About 41.3 inches of precipitation a year and 81 inches of snowfall (NOAA 1991–2020 normals, Colebrook 3sw station).

How hot do summers get in Colebrook, NH?

The average high peaks at 77 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 03576 have?

The USDA soil survey maps Tunbridge at the center of ZIP 03576: silt loam, well drained, pH about 5.4 (strongly acidic).

Did spring come early in Colebrook, NH in 2026?

Spring leaf-out near 03576 came on Apr 23 in 2026, 11 days earlier than the 1991–2020 average (May 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Colebrook, NH?

Long-day onions: the longest day near 03576 is 15 h 36 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).