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

Planting zone for 04780 — Smyrna Mills, ME

ZIP code 04780 (Smyrna Mills, Aroostook County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 13 and the first fall frost September 30.

Where ZIP 04780 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.

Zone4b−25 to −20 °F

Coldest night−31.7 to −28.9 °C

Last frostMay 13

First frostSep 30

2012 zone4a

Was 4a 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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Smyrna Mills, 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 Smyrna Mills, ME

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 13median — 50% chance of a later frost

Safe for tender plantsMay 30only 10% chance of frost after

First fall frostSeptember 30median — 10% chance by Sep 18

Growing season138 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 1 and returns around October 10.

From the NOAA station Patten 2, ME — 15 miles away, elevation 820 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 04780

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 1 – Apr 15

SpinachSow outdoors · Apr 1 – Apr 22

Broccoli, cabbageStart indoors · Mar 4 – Mar 18

Broccoli, cabbageTransplant · Apr 22 – May 6

Onion setsPlant outdoors · Apr 15 – Apr 29

PotatoesPlant outdoors · Apr 22 – May 6

LettuceSow outdoors · Apr 15 – Apr 29

Carrots, beetsSow outdoors · Apr 22 – May 6

TomatoesStart indoors · Mar 18 – Apr 1

TomatoesTransplant · May 20 – Jun 3

Peppers, eggplantStart indoors · Mar 4 – Mar 18

Peppers, eggplantTransplant · May 27 – Jun 10

BeansSow outdoors · May 20 – Jun 3

Sweet cornSow outdoors · May 20 – Jun 3

Cucumbers, squashSow outdoors · May 20 – Jun 3

Fall lettuce, spinachSow outdoors · Aug 5 – Aug 19

GarlicPlant cloves · Sep 16 – Oct 21

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 13) and first fall frost (Sep 30) 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 04780 came on Apr 28 — about the same time as the 1991–2020 average (Apr 30).

average
Apr 302026
Apr 28

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 Smyrna Mills, ME

The soil mapped at the center of ZIP 04780 is Thorndike — highly decomposed plant material, somewhat excessively drained.

TextureHighly decomposed plant materialtop layer

DrainageSomewhat excessively drainednatural drainage class

Organic matter53%high

Hydrologic groupDwater soaks in very slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Thorndike channery silt loam, 8 to 15 percent slopes, rocky.

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 04780; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Smyrna Mills, ME

Summer high76 °Faverage high, July

Winter low3 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights185nights a year at 32 °F or less

Growing degree days1,613base 50 °F — the season’s usable heat

Longest day15 h 47 mindaylight on June 21

Shortest day8 h 37 mindaylight on December 21

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

Precipitation44.1 inper year, rain and melted snow

Snowfall96 inper year; 126 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: Patten 2, ME (15 mi away); precipitation: Houlton 5n, ME (20 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.

Island Falls, ME · 14 mi

047614b

New Limerick, ME · 14 mi

047354b

Bridgewater, ME · 18 mi

047304b

Houlton, ME · 19 mi

047604a

Monticello, ME · 20 mi

047654b

Patten, ME · 20 mi

Maine planting zones →

Questions about 04780

What planting zone is ZIP code 04780?

ZIP code 04780 (Smyrna Mills, ME) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Smyrna Mills, ME?

The median last spring frost (32 °F) near 04780 is May 13; after May 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Patten 2 station.

When is the first frost in Smyrna Mills, ME?

The median first fall frost near 04780 is September 30, giving a median frost-free growing season of 138 days.

When should I plant tomatoes in 04780?

Start tomato seeds indoors around Mar 18 – Apr 1 and set transplants outside around May 20 – Jun 3, one to three weeks after the median last frost.

How much rain and snow does 04780 get?

About 44.1 inches of precipitation a year and 96 inches of snowfall (NOAA 1991–2020 normals, Houlton 5n station).

How hot do summers get in Smyrna Mills, ME?

The average high peaks at 76 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 04780 have?

The USDA soil survey maps Thorndike at the center of ZIP 04780: highly decomposed plant material, somewhat excessively drained.

Did spring come early in Smyrna Mills, ME in 2026?

Spring leaf-out near 04780 came on Apr 28 in 2026, about the same as the 1991–2020 average (Apr 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Smyrna Mills, ME?

Long-day onions: the longest day near 04780 is 15 h 47 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 04780 change?

Yes. The 2012 USDA map put 04780 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.