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

Planting zone for 03231 — East Andover, NH

ZIP code 03231 (East Andover, Merrimack County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 7 and the first fall frost October 3.

Where ZIP 03231 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostMay 7
First frostOct 3
2012 zone5a

Was 5a 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for East Andover, 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 East Andover, NH

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 20only 10% chance of frost after
First fall frostOctober 3median — 10% chance by Sep 24
Growing season148 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 13.

From the NOAA station Franklin Falls Dam, NH — 5 miles away, elevation 449 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 03231

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 8 – Aug 22
GarlicPlant cloves · Sep 19 – Oct 24
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 7) and first fall frost (Oct 3) 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 03231 came on Apr 15 — 6 days earlier than the 1991–2020 average (Apr 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).

Soil in East Andover, NH

The soil mapped at the center of ZIP 03231 is Adams — moderately decomposed plant material, somewhat excessively drained.

TextureModerately decomposed plant materialtop layer
DrainageSomewhat excessively drainednatural drainage class
Organic matter53%high
Hydrologic groupAwater soaks in fast
Farmland classFarmland of local importanceUSDA classification

Map unit: Adams loamy sand, 0 to 3 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 03231; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in East Andover, NH

Summer high82 °Faverage high, July
Winter low9 °Faverage low, January
Hot days7days a year at 90 °F or more
Freezing nights174nights a year at 32 °F or less
Growing degree days2,209base 50 °F — the season’s usable heat
Longest day15 h 25 mindaylight on June 21
Shortest day8 h 57 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation45.5 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 30 °F, low 9 °F 30°9° JanFebruary: average high 33 °F, low 10 °F 33°10° FebMarch: average high 42 °F, low 20 °F 42°20° MarApril: average high 56 °F, low 31 °F 56°31° AprMay: average high 68 °F, low 43 °F 68°43° MayJune: average high 76 °F, low 52 °F 76°52° JunJuly: average high 82 °F, low 58 °F 82°58° JulAugust: average high 80 °F, low 56 °F 80°56° AugSeptember: average high 72 °F, low 48 °F 72°48° SepOctober: average high 59 °F, low 37 °F 59°37° OctNovember: average high 46 °F, low 26 °F 46°26° NovDecember: average high 35 °F, low 17 °F 35°17° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.13 in precipitation 3.1 JanFebruary: 2.80 in precipitation 2.8 FebMarch: 3.31 in precipitation 3.3 MarApril: 3.49 in precipitation 3.5 AprMay: 3.62 in precipitation 3.6 MayJune: 4.28 in precipitation 4.3 JunJuly: 4.20 in precipitation 4.2 JulAugust: 4.07 in precipitation 4.1 AugSeptember: 3.72 in precipitation 3.7 SepOctober: 4.93 in precipitation 4.9 OctNovember: 3.93 in precipitation 3.9 NovDecember: 3.99 in precipitation 4.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Franklin Falls Dam, NH (5 mi away); precipitation: Franklin Falls Dam, NH (5 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.

032165b
Andover, NH · 2 mi
032355b
Franklin, NH · 4 mi
032685b
Salisbury, NH · 5 mi
032435b
Hill, NH · 5 mi
032305a
Danbury, NH · 8 mi
032875b
Wilmot, NH · 8 mi
032765b
Tilton, NH · 9 mi
032335b
Elkins, NH · 9 mi

New Hampshire planting zones →

Questions about 03231

What planting zone is ZIP code 03231?

ZIP code 03231 (East Andover, NH) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in East Andover, NH?

The median last spring frost (32 °F) near 03231 is May 7; after May 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Franklin Falls Dam station.

When is the first frost in East Andover, NH?

The median first fall frost near 03231 is October 3, giving a median frost-free growing season of 148 days.

When should I plant tomatoes in 03231?

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 03231 get?

About 45.5 inches of precipitation a year (NOAA 1991–2020 normals, Franklin Falls Dam station).

How hot do summers get in East Andover, NH?

The average high peaks at 82 °F in July, with about 7 days a year at 90 °F or more.

What kind of soil does 03231 have?

The USDA soil survey maps Adams at the center of ZIP 03231: moderately decomposed plant material, somewhat excessively drained.

Did spring come early in East Andover, NH in 2026?

Spring leaf-out near 03231 came on Apr 15 in 2026, 6 days earlier than the 1991–2020 average (Apr 21), according to the USA National Phenology Network Spring Index.

What kind of onions grow in East Andover, NH?

Long-day onions: the longest day near 03231 is 15 h 25 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 03231 change?

Yes. The 2012 USDA map put 03231 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.