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

Planting zone for 56633 — Cass Lake, MN

ZIP code 56633 (Cass Lake, Cass County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 17 and the first fall frost September 26.

Where ZIP 56633 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 17
First frostSep 26
2012 zone3a

Was 3a 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 3b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cass Lake, 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 Cass Lake, MN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 17median — 50% chance of a later frost
Safe for tender plantsMay 30only 10% chance of frost after
First fall frostSeptember 26median — 10% chance by Sep 12
Growing season131 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 7 and returns around October 6.

From the NOAA station Cass Lake, MN — 7 miles away, elevation 1,296 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 56633

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 5 – Apr 19
SpinachSow outdoors · Apr 5 – Apr 26
Broccoli, cabbageStart indoors · Mar 8 – Mar 22
Broccoli, cabbageTransplant · Apr 26 – May 10
Onion setsPlant outdoors · Apr 19 – May 3
PotatoesPlant outdoors · Apr 26 – May 10
LettuceSow outdoors · Apr 19 – May 3
Carrots, beetsSow outdoors · Apr 26 – May 10
TomatoesStart indoors · Mar 22 – Apr 5
TomatoesTransplant · May 24 – Jun 7
Peppers, eggplantStart indoors · Mar 8 – Mar 22
Peppers, eggplantTransplant · May 31 – Jun 14
BeansSow outdoors · May 24 – Jun 7
Sweet cornSow outdoors · May 24 – Jun 7
Cucumbers, squashSow outdoors · May 24 – Jun 7
Fall lettuce, spinachSow outdoors · Aug 1 – Aug 15
GarlicPlant cloves · Sep 12 – Oct 17
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 17) and first fall frost (Sep 26) 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 56633 came on Apr 23 — about the same time as the 1991–2020 average (Apr 25).

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 3b in Minnesota

287 plants native to the lower 48 states, recorded in Minnesota, and rated by the USDA to survive −35 °F or colder — the bottom of zone 3b. Each links to its USDA PLANTS profile.

Trees 33

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam fir60 ft · blooms mid summer · low shade tolerance · to −43 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fbigtooth aspen65 ft · blooms mid spring · high shade tolerance · to −43 °F

Shrubs 50

Allegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican mountain ash40 ft · blooms early summer · medium shade tolerance · to −38 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °F

Wildflowers & perennials 102

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °FAmerican vetch1.3 ft · blooms late spring · high shade tolerance · to −38 °F

Grasses 93

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbasin wildrye5 ft · blooms early spring · high shade tolerance · to −43 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 2

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °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 Cass Lake, MN.

Soil in Cass Lake, MN

The soil mapped at the center of ZIP 56633 is Warba — very fine sandy loam, well drained.

TextureVery fine sandy loamdrains and warms fast; dries out and needs more feeding
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Warba-Stuntz association, nearly level and undulating.

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 56633; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cass Lake, MN

Summer high79 °Faverage high, July
Winter low−4 °Faverage low, January
Hot days4days a year at 90 °F or more
Freezing nights187nights a year at 32 °F or less
Growing degree days2,027base 50 °F — the season’s usable heat
Longest day15 h 57 mindaylight on June 21
Shortest day8 h 28 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation26.5 inper year, rain and melted snow
Snowfall49 inper year

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 18 °F, low -4 °F 18°−4° JanFebruary: average high 24 °F, low 0 °F 24°0° FebMarch: average high 37 °F, low 15 °F 37°15° MarApril: average high 51 °F, low 29 °F 51°29° AprMay: average high 65 °F, low 42 °F 65°42° MayJune: average high 75 °F, low 53 °F 75°53° JunJuly: average high 79 °F, low 58 °F 79°58° JulAugust: average high 77 °F, low 56 °F 77°56° AugSeptember: average high 68 °F, low 47 °F 68°47° SepOctober: average high 52 °F, low 34 °F 52°34° OctNovember: average high 36 °F, low 20 °F 36°20° NovDecember: average high 23 °F, low 6 °F 23°6° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 0.76 in precipitation, 9.1 in snowfall 0.8❄9 JanFebruary: 0.74 in precipitation, 9.3 in snowfall 0.7❄9 FebMarch: 1.24 in precipitation, 6.2 in snowfall 1.2❄6 MarApril: 1.98 in precipitation, 5.6 in snowfall 2.0❄6 AprMay: 2.93 in precipitation 2.9 MayJune: 4.07 in precipitation 4.1 JunJuly: 3.74 in precipitation 3.7 JulAugust: 3.06 in precipitation 3.1 AugSeptember: 2.91 in precipitation 2.9 SepOctober: 2.76 in precipitation, 1.4 in snowfall 2.8❄1 OctNovember: 1.29 in precipitation, 5.8 in snowfall 1.3❄6 NovDecember: 1.01 in precipitation, 11.5 in snowfall 1.0❄12 Dec

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

Nearby ZIP codes

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

566633b
Pennington, MN · 13 mi
566413b
Federal Dam, MN · 14 mi
564364a
Benedict, MN · 14 mi
564844a
Walker, MN · 14 mi
564613b
Laporte, MN · 18 mi
566813b
Squaw Lake, MN · 20 mi
566013b
Bemidji, MN · 20 mi
566193b
Bemidji, MN · 21 mi

Minnesota planting zones →

Questions about 56633

What planting zone is ZIP code 56633?

ZIP code 56633 (Cass Lake, 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 Cass Lake, MN?

The median last spring frost (32 °F) near 56633 is May 17; after May 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cass Lake station.

When is the first frost in Cass Lake, MN?

The median first fall frost near 56633 is September 26, giving a median frost-free growing season of 131 days.

When should I plant tomatoes in 56633?

Start tomato seeds indoors around Mar 22 – Apr 5 and set transplants outside around May 24 – Jun 7, one to three weeks after the median last frost.

How much rain and snow does 56633 get?

About 26.5 inches of precipitation a year and 49 inches of snowfall (NOAA 1991–2020 normals, Cass Lake station).

How hot do summers get in Cass Lake, MN?

The average high peaks at 79 °F in July, with about 4 days a year at 90 °F or more.

What kind of soil does 56633 have?

The USDA soil survey maps Warba at the center of ZIP 56633: very fine sandy loam, well drained, pH about 5.8 (moderately acidic).

Did spring come early in Cass Lake, MN in 2026?

Spring leaf-out near 56633 came on Apr 23 in 2026, about the same as the 1991–2020 average (Apr 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cass Lake, MN?

Long-day onions: the longest day near 56633 is 15 h 57 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 56633 change?

Yes. The 2012 USDA map put 56633 in zone 3a; the 2023 map puts it in zone 3b. The newer map uses 1991–2020 data and more weather stations.