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

Planting zone for 04259 — Monmouth, ME

ZIP code 04259 (Monmouth, Kennebec County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 1 and the first fall frost October 11.

Where ZIP 04259 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 1
First frostOct 11
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Monmouth, 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 Monmouth, ME

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 1median — 50% chance of a later frost
Safe for tender plantsMay 14only 10% chance of frost after
First fall frostOctober 11median — 10% chance by Sep 30
Growing season163 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 19 and returns around October 25.

From the NOAA station Gardiner, ME — 11 miles away, elevation 135 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 04259

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 20 – Apr 3
SpinachSow outdoors · Mar 20 – Apr 10
Broccoli, cabbageStart indoors · Feb 20 – Mar 6
Broccoli, cabbageTransplant · Apr 10 – Apr 24
Onion setsPlant outdoors · Apr 3 – Apr 17
PotatoesPlant outdoors · Apr 10 – Apr 24
LettuceSow outdoors · Apr 3 – Apr 17
Carrots, beetsSow outdoors · Apr 10 – Apr 24
TomatoesStart indoors · Mar 6 – Mar 20
TomatoesTransplant · May 8 – May 22
Peppers, eggplantStart indoors · Feb 20 – Mar 6
Peppers, eggplantTransplant · May 15 – May 29
BeansSow outdoors · May 8 – May 22
Sweet cornSow outdoors · May 8 – May 22
Cucumbers, squashSow outdoors · May 8 – May 22
Fall lettuce, spinachSow outdoors · Aug 16 – Aug 30
GarlicPlant cloves · Sep 27 – Nov 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 1) and first fall frost (Oct 11) 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 04259 came on Apr 16 — 5 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 Monmouth, ME

The soil mapped at the center of ZIP 04259 is Paxton — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH4.8strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter4%moderate
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classFarmland of local importanceUSDA classification

Map unit: Paxton very stony fine sandy loam, 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 04259; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Monmouth, ME

Summer high81 °Faverage high, July
Winter low9 °Faverage low, January
Hot days5days a year at 90 °F or more
Freezing nights161nights a year at 32 °F or less
Growing degree days2,276base 50 °F — the season’s usable heat
Longest day15 h 31 mindaylight on June 21
Shortest day8 h 51 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation47.7 inper year, rain and melted snow
Snowfall69 inper year; 91 days with snow on the ground

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 21 °F 42°21° MarApril: average high 54 °F, low 33 °F 54°33° AprMay: average high 66 °F, low 44 °F 66°44° MayJune: average high 75 °F, low 54 °F 75°54° JunJuly: average high 81 °F, low 60 °F 81°60° JulAugust: average high 80 °F, low 58 °F 80°58° AugSeptember: average high 72 °F, low 50 °F 72°50° SepOctober: average high 60 °F, low 39 °F 60°39° OctNovember: average high 47 °F, low 29 °F 47°29° NovDecember: average high 36 °F, low 18 °F 36°18° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 3.58 in precipitation, 17.6 in snowfall 3.6❄18 JanFebruary: 2.95 in precipitation, 20 in snowfall 3.0❄20 FebMarch: 3.71 in precipitation, 12.7 in snowfall 3.7❄13 MarApril: 4.18 in precipitation, 2.8 in snowfall 4.2❄3 AprMay: 3.66 in precipitation 3.7 MayJune: 4.40 in precipitation 4.4 JunJuly: 3.42 in precipitation 3.4 JulAugust: 3.61 in precipitation 3.6 AugSeptember: 3.93 in precipitation 3.9 SepOctober: 5.39 in precipitation, 0.2 in snowfall 5.4 OctNovember: 4.52 in precipitation, 2.3 in snowfall 4.5❄2 NovDecember: 4.38 in precipitation, 13.3 in snowfall 4.4❄13 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Gardiner, ME (11 mi away); precipitation: Gardiner, ME (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

042655b
North Monmouth, ME · 3 mi
043505b
Litchfield, ME · 6 mi
043645b
Winthrop, ME · 6 mi
042365b
Greene, ME · 7 mi
042635b
Leeds, ME · 7 mi
042845b
Wayne, ME · 8 mi
042805b
Sabattus, ME · 8 mi
043435b
East Winthrop, ME · 8 mi

Maine planting zones →

Questions about 04259

What planting zone is ZIP code 04259?

ZIP code 04259 (Monmouth, ME) 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 Monmouth, ME?

The median last spring frost (32 °F) near 04259 is May 1; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Gardiner station.

When is the first frost in Monmouth, ME?

The median first fall frost near 04259 is October 11, giving a median frost-free growing season of 163 days.

When should I plant tomatoes in 04259?

Start tomato seeds indoors around Mar 6 – Mar 20 and set transplants outside around May 8 – May 22, one to three weeks after the median last frost.

How much rain and snow does 04259 get?

About 47.7 inches of precipitation a year and 69 inches of snowfall (NOAA 1991–2020 normals, Gardiner station).

How hot do summers get in Monmouth, ME?

The average high peaks at 81 °F in July, with about 5 days a year at 90 °F or more.

What kind of soil does 04259 have?

The USDA soil survey maps Paxton at the center of ZIP 04259: fine sandy loam, well drained, pH about 4.8 (strongly acidic).

Did spring come early in Monmouth, ME in 2026?

Spring leaf-out near 04259 came on Apr 16 in 2026, 5 days earlier than the 1991–2020 average (Apr 21), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Monmouth, ME?

Long-day onions: the longest day near 04259 is 15 h 31 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).