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

Planting zone for 03901 — Berwick, ME

ZIP code 03901 (Berwick, York County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 30 and the first fall frost October 9.

Where ZIP 03901 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 frostApr 30
First frostOct 9
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 Berwick, ME…

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 Berwick, ME

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 30median — 50% chance of a later frost
Safe for tender plantsMay 13only 10% chance of frost after
First fall frostOctober 9median — 10% chance by Sep 27
Growing season161 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 17 and returns around October 23.

From the NOAA station Rochester Skyhaven Airport, NH — 4 miles away, elevation 325 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 03901

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 19 – Apr 2
SpinachSow outdoors · Mar 19 – Apr 9
Broccoli, cabbageStart indoors · Feb 19 – Mar 5
Broccoli, cabbageTransplant · Apr 9 – Apr 23
Onion setsPlant outdoors · Apr 2 – Apr 16
PotatoesPlant outdoors · Apr 9 – Apr 23
LettuceSow outdoors · Apr 2 – Apr 16
Carrots, beetsSow outdoors · Apr 9 – Apr 23
TomatoesStart indoors · Mar 5 – Mar 19
TomatoesTransplant · May 7 – May 21
Peppers, eggplantStart indoors · Feb 19 – Mar 5
Peppers, eggplantTransplant · May 14 – May 28
BeansSow outdoors · May 7 – May 21
Sweet cornSow outdoors · May 7 – May 21
Cucumbers, squashSow outdoors · May 7 – May 21
Fall lettuce, spinachSow outdoors · Aug 14 – Aug 28
GarlicPlant cloves · Sep 25 – Oct 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 9) 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 03901 came on Apr 15 — about the same time as the 1991–2020 average (Apr 16).

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 6a in Maine

502 plants native to the lower 48 states, recorded in Maine, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 55

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 101

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °F

Wildflowers & perennials 173

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °F

Grasses 154

alpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °F

Vines 6

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °F

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 Berwick, ME.

Soil in Berwick, ME

The soil mapped at the center of ZIP 03901 is Brayton — highly decomposed plant material, poorly drained.

TextureHighly decomposed plant materialtop layer
pH4.0strongly acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter53%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Brayton and Westbury very stony fine sandy loams, 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 03901; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Berwick, ME

Summer high82 °Faverage high, July
Winter low15 °Faverage low, January
Hot days11days a year at 90 °F or more
Freezing nights145nights a year at 32 °F or less
Growing degree days2,438base 50 °F — the season’s usable heat
Longest day15 h 24 mindaylight on June 21
Shortest day8 h 58 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation41.2 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 33 °F, low 15 °F 33°15° JanFebruary: average high 35 °F, low 17 °F 35°17° FebMarch: average high 44 °F, low 25 °F 44°25° MarApril: average high 57 °F, low 35 °F 57°35° AprMay: average high 67 °F, low 45 °F 67°45° MayJune: average high 77 °F, low 54 °F 77°54° JunJuly: average high 82 °F, low 60 °F 82°60° JulAugust: average high 81 °F, low 58 °F 81°58° AugSeptember: average high 73 °F, low 50 °F 73°50° SepOctober: average high 60 °F, low 39 °F 60°39° OctNovember: average high 48 °F, low 31 °F 48°31° NovDecember: average high 37 °F, low 22 °F 37°22° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.53 in precipitation 2.5 JanFebruary: 2.22 in precipitation 2.2 FebMarch: 3.72 in precipitation 3.7 MarApril: 3.67 in precipitation 3.7 AprMay: 3.52 in precipitation 3.5 MayJune: 3.86 in precipitation 3.9 JunJuly: 3.52 in precipitation 3.5 JulAugust: 3.17 in precipitation 3.2 AugSeptember: 3.43 in precipitation 3.4 SepOctober: 4.39 in precipitation 4.4 OctNovember: 3.89 in precipitation 3.9 NovDecember: 3.30 in precipitation 3.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Rochester Skyhaven Airport, NH (4 mi away); precipitation: Rochester Skyhaven Airport, NH (4 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.

038786a
Somersworth, NH · 4 mi
039065b
North Berwick, ME · 5 mi
038686a
Rochester, NH · 5 mi
038696a
Rollinsford, NH · 5 mi
039086a
South Berwick, ME · 7 mi
038666a
Rochester, NH · 7 mi
038216a
Dover, NH · 7 mi
038226a
Dover, NH · 7 mi

Maine planting zones →

Questions about 03901

What planting zone is ZIP code 03901?

ZIP code 03901 (Berwick, ME) 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 Berwick, ME?

The median last spring frost (32 °F) near 03901 is April 30; after May 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Rochester Skyhaven Airport station.

When is the first frost in Berwick, ME?

The median first fall frost near 03901 is October 9, giving a median frost-free growing season of 161 days.

When should I plant tomatoes in 03901?

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

How much rain and snow does 03901 get?

About 41.2 inches of precipitation a year (NOAA 1991–2020 normals, Rochester Skyhaven Airport station).

How hot do summers get in Berwick, ME?

The average high peaks at 82 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 03901 have?

The USDA soil survey maps Brayton at the center of ZIP 03901: highly decomposed plant material, poorly drained, pH about 4.0 (strongly acidic).

Did spring come early in Berwick, ME in 2026?

Spring leaf-out near 03901 came on Apr 15 in 2026, about the same as the 1991–2020 average (Apr 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Berwick, ME?

Long-day onions: the longest day near 03901 is 15 h 24 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 03901 change?

Yes. The 2012 USDA map put 03901 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.