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

Planting zone for 58845 — Grenora, ND

ZIP code 58845 (Grenora, Williams County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 18 and the first fall frost September 21.

Where ZIP 58845 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 18
First frostSep 21
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 Grenora, ND…

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 Grenora, ND

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 18median — 50% chance of a later frost
Safe for tender plantsMay 30only 10% chance of frost after
First fall frostSeptember 21median — 10% chance by Sep 7
Growing season125 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around September 28.

From the NOAA station Westby, MT — 17 miles away, elevation 2,103 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 58845

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 6 – Apr 20
SpinachSow outdoors · Apr 6 – Apr 27
Broccoli, cabbageStart indoors · Mar 9 – Mar 23
Broccoli, cabbageTransplant · Apr 27 – May 11
Onion setsPlant outdoors · Apr 20 – May 4
PotatoesPlant outdoors · Apr 27 – May 11
LettuceSow outdoors · Apr 20 – May 4
Carrots, beetsSow outdoors · Apr 27 – May 11
TomatoesStart indoors · Mar 23 – Apr 6
TomatoesTransplant · May 25 – Jun 8
Peppers, eggplantStart indoors · Mar 9 – Mar 23
Peppers, eggplantTransplant · Jun 1 – Jun 15
BeansSow outdoors · May 25 – Jun 8
Sweet cornSow outdoors · May 25 – Jun 8
Cucumbers, squashSow outdoors · May 25 – Jun 8
Fall lettuce, spinachSow outdoors · Jul 27 – Aug 10
GarlicPlant cloves · Sep 7 – Oct 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 18) and first fall frost (Sep 21) 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 58845 came on Apr 21 — 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).

Native plants for zone 3b in North Dakota

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

Trees 20

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fbigtooth aspen65 ft · blooms mid spring · high shade tolerance · to −43 °Fblack ash65 ft · blooms early spring · high shade tolerance · to −47 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °F

Shrubs 42

American black currant3 ft · blooms early spring · to −46 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °Fbig sagebrush4 ft · blooms mid summer · high shade tolerance · to −43 °Fblack hawthorn15 ft · blooms mid spring · medium shade tolerance · to −47 °Fbog birch20 ft · blooms mid spring · high shade tolerance · to −38 °F

Wildflowers & perennials 91

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °FAmerican vetch1.3 ft · blooms late spring · high shade tolerance · to −38 °FAmerican water horehound1.8 ft · blooms early summer · low shade tolerance · to −38 °F

Grasses 88

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °Fawlfruit sedge4 ft · blooms mid 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 3

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Fwestern white clematis1 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 Grenora, ND.

Soil in Grenora, ND

The soil mapped at the center of ZIP 58845 is Zahl — loam, well drained.

TextureLoama good balance for most vegetables
pH7.8slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Zahl-Williams loams, 6 to 9 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 58845; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Grenora, ND

Summer high80 °Faverage high, July
Winter low−2 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights202nights a year at 32 °F or less
Growing degree days1,797base 50 °F — the season’s usable heat
Longest day16 h 09 mindaylight on June 21
Shortest day8 h 16 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation14.9 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 20 °F, low -2 °F 20°−2° JanFebruary: average high 24 °F, low 2 °F 24°2° FebMarch: average high 36 °F, low 14 °F 36°14° MarApril: average high 53 °F, low 27 °F 53°27° AprMay: average high 65 °F, low 40 °F 65°40° MayJune: average high 73 °F, low 50 °F 73°50° JunJuly: average high 80 °F, low 55 °F 80°55° JulAugust: average high 80 °F, low 52 °F 80°52° AugSeptember: average high 70 °F, low 41 °F 70°41° SepOctober: average high 54 °F, low 29 °F 54°29° OctNovember: average high 36 °F, low 15 °F 36°15° NovDecember: average high 24 °F, low 4 °F 24°4° Dec

Precipitation by month inches

0″1″2″3″4″January: 0.37 in precipitation 0.4 JanFebruary: 0.34 in precipitation 0.3 FebMarch: 0.55 in precipitation 0.6 MarApril: 0.98 in precipitation 1.0 AprMay: 2.17 in precipitation 2.2 MayJune: 3.14 in precipitation 3.1 JunJuly: 2.49 in precipitation 2.5 JulAugust: 1.64 in precipitation 1.6 AugSeptember: 1.26 in precipitation 1.3 SepOctober: 0.97 in precipitation 1.0 OctNovember: 0.52 in precipitation 0.5 NovDecember: 0.48 in precipitation 0.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Westby, MT (17 mi away); precipitation: Westby, MT (17 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.

588564a
Zahl, ND · 9 mi
592193b
Dagmar, MT · 12 mi
588443b
Fortuna, ND · 19 mi
592753b
Westby, MT · 20 mi
592113b
Antelope, MT · 20 mi
588303b
Alamo, ND · 21 mi
588334a
Ambrose, ND · 25 mi
588014a
Williston, ND · 29 mi

North Dakota planting zones →

Questions about 58845

What planting zone is ZIP code 58845?

ZIP code 58845 (Grenora, ND) 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 Grenora, ND?

The median last spring frost (32 °F) near 58845 is May 18; after May 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Westby station.

When is the first frost in Grenora, ND?

The median first fall frost near 58845 is September 21, giving a median frost-free growing season of 125 days.

When should I plant tomatoes in 58845?

Start tomato seeds indoors around Mar 23 – Apr 6 and set transplants outside around May 25 – Jun 8, one to three weeks after the median last frost.

How much rain and snow does 58845 get?

About 14.9 inches of precipitation a year (NOAA 1991–2020 normals, Westby station).

How hot do summers get in Grenora, ND?

The average high peaks at 80 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 58845 have?

The USDA soil survey maps Zahl at the center of ZIP 58845: loam, well drained, pH about 7.8 (slightly alkaline).

Did spring come early in Grenora, ND in 2026?

Spring leaf-out near 58845 came on Apr 21 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 Grenora, ND?

Long-day onions: the longest day near 58845 is 16 h 09 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).