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

Planting zone for 73933 — Boise City, OK

ZIP code 73933 (Boise City, Cimarron County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 26 and the first fall frost October 17.

Where ZIP 73933 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 26
First frostOct 17
2012 zone6b

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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Boise City, OK…

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 Boise City, OK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 26median — 50% chance of a later frost
Safe for tender plantsMay 9only 10% chance of frost after
First fall frostOctober 17median — 10% chance by Oct 4
Growing season173 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 15 and returns around October 25.

From the NOAA station Boise City 2 E, OK — 6 miles away, elevation 4,134 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 73933

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 15 – Mar 29
SpinachSow outdoors · Mar 15 – Apr 5
Broccoli, cabbageStart indoors · Feb 15 – Mar 1
Broccoli, cabbageTransplant · Apr 5 – Apr 19
Onion setsPlant outdoors · Mar 29 – Apr 12
PotatoesPlant outdoors · Apr 5 – Apr 19
LettuceSow outdoors · Mar 29 – Apr 12
Carrots, beetsSow outdoors · Apr 5 – Apr 19
TomatoesStart indoors · Mar 1 – Mar 15
TomatoesTransplant · May 3 – May 17
Peppers, eggplantStart indoors · Feb 15 – Mar 1
Peppers, eggplantTransplant · May 10 – May 24
BeansSow outdoors · May 3 – May 17
Sweet cornSow outdoors · May 3 – May 17
Cucumbers, squashSow outdoors · May 3 – May 17
Fall lettuce, spinachSow outdoors · Aug 22 – Sep 5
GarlicPlant cloves · Oct 3 – Nov 7
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Oct 17) 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 73933 came on Feb 19 — 16 days earlier than the 1991–2020 average (Mar 7).

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 6b in Oklahoma

489 plants native to the lower 48 states, recorded in Oklahoma, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 57

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 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °FArizona walnut50 ft · blooms late spring · high shade tolerance · to −33 °Fbald cypress130 ft · blooms mid spring · medium shade tolerance · to −18 °F

Shrubs 85

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °F

Wildflowers & perennials 182

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °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 lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 145

alkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °FArizona cottontop4 ft · blooms late summer · high shade tolerance · to −13 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °F

Vines 13

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Fheartleaf peppervine2 ft · blooms late spring · low shade tolerance · to −8 °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 Boise City, OK.

Soil in Boise City, OK

The soil mapped at the center of ZIP 73933 is Sherm — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH7.2neutral; 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: Sherm clay loam, 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 73933; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Boise City, OK

Summer high94 °Faverage high, July
Winter low20 °Faverage low, January
Hot days74days a year at 90 °F or more
Freezing nights135nights a year at 32 °F or less
Growing degree days4,009base 50 °F — the season’s usable heat
Longest day14 h 41 mindaylight on June 21
Shortest day9 h 38 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation18.3 inper year, rain and melted snow
Snowfall32 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 52 °F, low 20 °F 52°20° JanFebruary: average high 56 °F, low 23 °F 56°23° FebMarch: average high 64 °F, low 30 °F 64°30° MarApril: average high 72 °F, low 38 °F 72°38° AprMay: average high 80 °F, low 47 °F 80°47° MayJune: average high 90 °F, low 58 °F 90°58° JunJuly: average high 94 °F, low 63 °F 94°63° JulAugust: average high 91 °F, low 62 °F 91°62° AugSeptember: average high 85 °F, low 54 °F 85°54° SepOctober: average high 74 °F, low 40 °F 74°40° OctNovember: average high 61 °F, low 29 °F 61°29° NovDecember: average high 51 °F, low 22 °F 51°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.50 in precipitation, 7.3 in snowfall 0.5❄7 JanFebruary: 0.36 in precipitation, 2.5 in snowfall 0.4❄3 FebMarch: 1.10 in precipitation, 7.2 in snowfall 1.1❄7 MarApril: 1.40 in precipitation, 2.3 in snowfall 1.4❄2 AprMay: 1.82 in precipitation, 0.2 in snowfall 1.8 MayJune: 2.28 in precipitation 2.3 JunJuly: 3.12 in precipitation 3.1 JulAugust: 3.23 in precipitation 3.2 AugSeptember: 1.75 in precipitation 1.8 SepOctober: 1.48 in precipitation, 1.3 in snowfall 1.5❄1 OctNovember: 0.56 in precipitation, 3.1 in snowfall 0.6❄3 NovDecember: 0.74 in precipitation, 7.9 in snowfall 0.7❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Boise City 2 E, OK (6 mi away); precipitation: Boise City 2 E, OK (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

739376b
Felt, OK · 16 mi
739466b
Kenton, OK · 18 mi
739476b
Keyes, OK · 24 mi
810296b
Campo, CO · 24 mi
790516b
Kerrick, TX · 28 mi
790876b
Texline, TX · 35 mi
810646b
Pritchett, CO · 41 mi
790226b
Dalhart, TX · 44 mi

Oklahoma planting zones →

Questions about 73933

What planting zone is ZIP code 73933?

ZIP code 73933 (Boise City, OK) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Boise City, OK?

The median last spring frost (32 °F) near 73933 is April 26; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Boise City 2 E station.

When is the first frost in Boise City, OK?

The median first fall frost near 73933 is October 17, giving a median frost-free growing season of 173 days.

When should I plant tomatoes in 73933?

Start tomato seeds indoors around Mar 1 – Mar 15 and set transplants outside around May 3 – May 17, one to three weeks after the median last frost.

How much rain and snow does 73933 get?

About 18.3 inches of precipitation a year and 32 inches of snowfall (NOAA 1991–2020 normals, Boise City 2 E station).

How hot do summers get in Boise City, OK?

The average high peaks at 94 °F in July, with about 74 days a year at 90 °F or more.

What kind of soil does 73933 have?

The USDA soil survey maps Sherm at the center of ZIP 73933: clay loam, well drained, pH about 7.2 (neutral).

Did spring come early in Boise City, OK in 2026?

Spring leaf-out near 73933 came on Feb 19 in 2026, 16 days earlier than the 1991–2020 average (Mar 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Boise City, OK?

Intermediate onions: the longest day near 73933 is 14 h 41 min, so day-neutral types bulb best; long-day varieties may not bulb fully.