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

Planting zone for 58276 — Saint Thomas, ND

ZIP code 58276 (Saint Thomas, Pembina County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 4 and the first fall frost October 7.

Where ZIP 58276 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 4
First frostOct 7
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 Saint Thomas, 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 Saint Thomas, ND

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 4median — 50% chance of a later frost
Safe for tender plantsMay 18only 10% chance of frost after
First fall frostOctober 7median — 10% chance by Sep 25
Growing season156 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 24 and returns around October 17.

From the NOAA station Grafton, ND — 14 miles away, elevation 827 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 58276

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 23 – Apr 6
SpinachSow outdoors · Mar 23 – Apr 13
Broccoli, cabbageStart indoors · Feb 23 – Mar 9
Broccoli, cabbageTransplant · Apr 13 – Apr 27
Onion setsPlant outdoors · Apr 6 – Apr 20
PotatoesPlant outdoors · Apr 13 – Apr 27
LettuceSow outdoors · Apr 6 – Apr 20
Carrots, beetsSow outdoors · Apr 13 – Apr 27
TomatoesStart indoors · Mar 9 – Mar 23
TomatoesTransplant · May 11 – May 25
Peppers, eggplantStart indoors · Feb 23 – Mar 9
Peppers, eggplantTransplant · May 18 – Jun 1
BeansSow outdoors · May 11 – May 25
Sweet cornSow outdoors · May 11 – May 25
Cucumbers, squashSow outdoors · May 11 – May 25
Fall lettuce, spinachSow outdoors · Aug 12 – Aug 26
GarlicPlant cloves · Sep 23 – Oct 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 4) and first fall frost (Oct 7) 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 58276 came on May 4 — 8 days later than the 1991–2020 average (Apr 26).

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 4a in North Dakota

342 plants native to the lower 48 states, recorded in North Dakota, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. Each links to its USDA PLANTS profile.

Trees 21

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 56

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °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 °F

Wildflowers & perennials 146

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °F

Grasses 110

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 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 4

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °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 Saint Thomas, ND.

Soil in Saint Thomas, ND

The soil mapped at the center of ZIP 58276 is Bearden — silty clay loam, somewhat poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH7.6slightly alkaline; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter5%high
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Bearden silty clay loam, 0 to 2 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 58276; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Thomas, ND

Summer high81 °Faverage high, July
Winter low0 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights169nights a year at 32 °F or less
Growing degree days2,527base 50 °F — the season’s usable heat
Longest day16 h 09 mindaylight on June 21
Shortest day8 h 17 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation20 inper year, rain and melted snow
Snowfall39 inper year; 125 days with snow on the ground

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 16 °F, low 0 °F 16°0° JanFebruary: average high 21 °F, low 4 °F 21°4° FebMarch: average high 34 °F, low 19 °F 34°19° MarApril: average high 53 °F, low 33 °F 53°33° AprMay: average high 68 °F, low 46 °F 68°46° MayJune: average high 79 °F, low 57 °F 79°57° JunJuly: average high 81 °F, low 61 °F 81°61° JulAugust: average high 80 °F, low 59 °F 80°59° AugSeptember: average high 71 °F, low 50 °F 71°50° SepOctober: average high 54 °F, low 36 °F 54°36° OctNovember: average high 36 °F, low 22 °F 36°22° NovDecember: average high 21 °F, low 7 °F 21°7° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.34 in precipitation, 7.4 in snowfall 0.3❄7 JanFebruary: 0.34 in precipitation, 4.6 in snowfall 0.3❄5 FebMarch: 0.71 in precipitation, 5.7 in snowfall 0.7❄6 MarApril: 1.11 in precipitation, 3.4 in snowfall 1.1❄3 AprMay: 2.87 in precipitation, 0.9 in snowfall 2.9❄1 MayJune: 3.77 in precipitation 3.8 JunJuly: 3.44 in precipitation 3.4 JulAugust: 2.25 in precipitation 2.3 AugSeptember: 2.31 in precipitation 2.3 SepOctober: 1.66 in precipitation, 2.5 in snowfall 1.7❄3 OctNovember: 0.72 in precipitation, 5.9 in snowfall 0.7❄6 NovDecember: 0.50 in precipitation, 8.7 in snowfall 0.5❄9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Grafton, ND (14 mi away); precipitation: Cavalier 7nw, ND (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.

582364a
Glasston, ND · 7 mi
582224a
Crystal, ND · 10 mi
582254a
Drayton, ND · 11 mi
582384a
Hamilton, ND · 11 mi
582414a
Hensel, ND · 13 mi
582434a
Hoople, ND · 13 mi
582374a
Grafton, ND · 15 mi
582163b
Bathgate, ND · 18 mi

North Dakota planting zones →

Questions about 58276

What planting zone is ZIP code 58276?

ZIP code 58276 (Saint Thomas, ND) 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 Saint Thomas, ND?

The median last spring frost (32 °F) near 58276 is May 4; after May 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Grafton station.

When is the first frost in Saint Thomas, ND?

The median first fall frost near 58276 is October 7, giving a median frost-free growing season of 156 days.

When should I plant tomatoes in 58276?

Start tomato seeds indoors around Mar 9 – Mar 23 and set transplants outside around May 11 – May 25, one to three weeks after the median last frost.

How much rain and snow does 58276 get?

About 20 inches of precipitation a year and 39 inches of snowfall (NOAA 1991–2020 normals, Cavalier 7nw station).

How hot do summers get in Saint Thomas, ND?

The average high peaks at 81 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 58276 have?

The USDA soil survey maps Bearden at the center of ZIP 58276: silty clay loam, somewhat poorly drained, pH about 7.6 (slightly alkaline).

Did spring come early in Saint Thomas, ND in 2026?

Spring leaf-out near 58276 came on May 4 in 2026, 8 days later than the 1991–2020 average (Apr 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint Thomas, ND?

Long-day onions: the longest day near 58276 is 16 h 09 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 58276 change?

Yes. The 2012 USDA map put 58276 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.