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

Planting zone for 56584 — Twin Valley, MN

ZIP code 56584 (Twin Valley, Norman County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 11 and the first fall frost September 27.

Where ZIP 56584 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.

Zone4a−30 to −25 °F
Coldest night−34.4 to −31.7 °C
Last frostMay 11
First frostSep 27
2012 zone3b

Was 3b 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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Twin Valley, 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 Twin Valley, MN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 11median — 50% chance of a later frost
Safe for tender plantsMay 25only 10% chance of frost after
First fall frostSeptember 27median — 10% chance by Sep 14
Growing season137 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 2 and returns around October 6.

From the NOAA station Ada, MN — 14 miles away, elevation 909 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 56584

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 30 – Apr 13
SpinachSow outdoors · Mar 30 – Apr 20
Broccoli, cabbageStart indoors · Mar 2 – Mar 16
Broccoli, cabbageTransplant · Apr 20 – May 4
Onion setsPlant outdoors · Apr 13 – Apr 27
PotatoesPlant outdoors · Apr 20 – May 4
LettuceSow outdoors · Apr 13 – Apr 27
Carrots, beetsSow outdoors · Apr 20 – May 4
TomatoesStart indoors · Mar 16 – Mar 30
TomatoesTransplant · May 18 – Jun 1
Peppers, eggplantStart indoors · Mar 2 – Mar 16
Peppers, eggplantTransplant · May 25 – Jun 8
BeansSow outdoors · May 18 – Jun 1
Sweet cornSow outdoors · May 18 – Jun 1
Cucumbers, squashSow outdoors · May 18 – Jun 1
Fall lettuce, spinachSow outdoors · Aug 2 – Aug 16
GarlicPlant cloves · Sep 13 – Oct 18
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 11) and first fall frost (Sep 27) 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 56584 came on Apr 23 — about the same time as the 1991–2020 average (Apr 22).

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 Twin Valley, MN

The soil mapped at the center of ZIP 56584 is Augsburg — silt loam, very poorly drained.

TextureSilt loama good balance for most vegetables
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter8%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Augsburg, Borup and Colvin soils, very poorly drained, 0 to 1 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 56584; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Twin Valley, MN

Summer high81 °Faverage high, July
Winter low−4 °Faverage low, January
Hot days8days a year at 90 °F or more
Freezing nights180nights a year at 32 °F or less
Growing degree days2,111base 50 °F — the season’s usable heat
Longest day15 h 56 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 inper year, rain and melted snow

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 16 °F, low -4 °F 16°−4° JanFebruary: average high 21 °F, low -1 °F 21°−1° FebMarch: average high 35 °F, low 14 °F 35°14° MarApril: average high 53 °F, low 30 °F 53°30° AprMay: average high 67 °F, low 42 °F 67°42° MayJune: average high 77 °F, low 53 °F 77°53° JunJuly: average high 81 °F, low 57 °F 81°57° JulAugust: average high 80 °F, low 54 °F 80°54° AugSeptember: average high 71 °F, low 46 °F 71°46° SepOctober: average high 55 °F, low 33 °F 55°33° OctNovember: average high 37 °F, low 19 °F 37°19° NovDecember: average high 22 °F, low 5 °F 22°5° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 0.73 in precipitation 0.7 JanFebruary: 0.63 in precipitation 0.6 FebMarch: 1.04 in precipitation 1.0 MarApril: 1.63 in precipitation 1.6 AprMay: 3.42 in precipitation 3.4 MayJune: 4.49 in precipitation 4.5 JunJuly: 3.67 in precipitation 3.7 JulAugust: 3.40 in precipitation 3.4 AugSeptember: 2.83 in precipitation 2.8 SepOctober: 2.44 in precipitation 2.4 OctNovember: 0.87 in precipitation 0.9 NovDecember: 0.83 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Ada, MN (14 mi away); precipitation: Twin Valley 0.1 Ne, MN (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4a.

565414a
Flom, MN · 6 mi
565854a
Ulen, MN · 9 mi
565454a
Gary, MN · 12 mi
565194a
Borup, MN · 12 mi
565524a
Hitterdal, MN · 16 mi
565574a
Mahnomen, MN · 20 mi
565164a
Bejou, MN · 20 mi
565914a
White Earth, MN · 20 mi

Minnesota planting zones →

Questions about 56584

What planting zone is ZIP code 56584?

ZIP code 56584 (Twin Valley, MN) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Twin Valley, MN?

The median last spring frost (32 °F) near 56584 is May 11; after May 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ada station.

When is the first frost in Twin Valley, MN?

The median first fall frost near 56584 is September 27, giving a median frost-free growing season of 137 days.

When should I plant tomatoes in 56584?

Start tomato seeds indoors around Mar 16 – Mar 30 and set transplants outside around May 18 – Jun 1, one to three weeks after the median last frost.

How much rain and snow does 56584 get?

About 26 inches of precipitation a year (NOAA 1991–2020 normals, Twin Valley 0.1 Ne station).

How hot do summers get in Twin Valley, MN?

The average high peaks at 81 °F in July, with about 8 days a year at 90 °F or more.

What kind of soil does 56584 have?

The USDA soil survey maps Augsburg at the center of ZIP 56584: silt loam, very poorly drained, pH about 7.9 (alkaline).

Did spring come early in Twin Valley, MN in 2026?

Spring leaf-out near 56584 came on Apr 23 in 2026, about the same as the 1991–2020 average (Apr 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Twin Valley, MN?

Long-day onions: the longest day near 56584 is 15 h 56 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 56584 change?

Yes. The 2012 USDA map put 56584 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.