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

Planting zone for 55607 — Isabella, MN

ZIP code 55607 (Isabella, Lake County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 31 and the first fall frost September 15.

Where ZIP 55607 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.

Zone3b−35 to −30 °F

Coldest night−37.2 to −34.4 °C

Last frostMay 31

First frostSep 15

2012 zone3b

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 3b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Isabella, MN…

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 Isabella, MN

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 21only 10% chance of frost after

First fall frostSeptember 15median — 10% chance by Aug 30

Growing season104 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 16 and returns around September 25.

From the NOAA station Isabella 14w, MN — 7 miles away, elevation 1,739 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 55607

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 21 – Aug 4

GarlicPlant cloves · Sep 1 – Oct 6

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 31) and first fall frost (Sep 15) 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 55607 came on May 9 — 7 days later than the 1991–2020 average (May 2).

average
May 22026
May 9

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 Isabella, MN

The soil mapped at the center of ZIP 55607 is Bowstring — muck, very poorly drained.

TextureMucktop layer

DrainageVery poorly drainedconsider raised beds

Organic matter65%high

Hydrologic groupA/Ddrains fast once dried out; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Bowstring and Fluvaquents, loamy, 0 to 2 percent slopes, frequently flooded.

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 55607; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Isabella, MN

Summer high76 °Faverage high, July

Winter low−5 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights206nights a year at 32 °F or less

Growing degree days1,487base 50 °F — the season’s usable heat

Longest day15 h 59 mindaylight on June 21

Shortest day8 h 25 mindaylight on December 21

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

Precipitation29.9 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Isabella 14w, MN (7 mi away); precipitation: Isabella 14w, MN (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

556034a

Finland, MN · 15 mi

556144a

Silver Bay, MN · 20 mi

557503b

Hoyt Lakes, MN · 22 mi

Two Harbors, MN · 27 mi

556014a

Beaver Bay, MN · 27 mi

557313b

Ely, MN · 28 mi

Minnesota planting zones →

Questions about 55607

What planting zone is ZIP code 55607?

ZIP code 55607 (Isabella, MN) is in USDA hardiness zone 3b on the 2023 map: the coldest night of an average winter reaches −35 to −30 °F (−37.2 to −34.4 °C).

When is the last frost in Isabella, MN?

The median last spring frost (32 °F) near 55607 is May 31; after June 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Isabella 14w station.

When is the first frost in Isabella, MN?

The median first fall frost near 55607 is September 15, giving a median frost-free growing season of 104 days.

When should I plant tomatoes in 55607?

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 55607 get?

About 29.9 inches of precipitation a year (NOAA 1991–2020 normals, Isabella 14w station).

How hot do summers get in Isabella, MN?

The average high peaks at 76 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 55607 have?

The USDA soil survey maps Bowstring at the center of ZIP 55607: muck, very poorly drained.

Did spring come early in Isabella, MN in 2026?

Spring leaf-out near 55607 came on May 9 in 2026, 7 days later than the 1991–2020 average (May 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Isabella, MN?

Long-day onions: the longest day near 55607 is 15 h 59 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).