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

Planting zone for Duncan, OK

Duncan, OK is in USDA zone 8a across its 3 ZIP codes. The median last spring frost is March 25 and the first fall frost November 7.

Duncan on the zone map

Outlined: its 1 ZIP code areas · 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.

Zone8a10 to 15 °F
ZIP codes3
Last frostMar 25
First frostNov 7
Growing season225 days

8a 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Duncan, OK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 25median — 50% chance of a later frost
Safe for tender plantsApril 12only 10% chance of frost after
First fall frostNovember 7median — 10% chance by Oct 22
Growing season225 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 11 and returns around November 16.

From the NOAA station Duncan, OK, elevation 1,125 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 Duncan

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 11 – Feb 25
SpinachSow outdoors · Feb 11 – Mar 4
Broccoli, cabbageStart indoors · Jan 14 – Jan 28
Broccoli, cabbageTransplant · Mar 4 – Mar 18
Onion setsPlant outdoors · Feb 25 – Mar 11
PotatoesPlant outdoors · Mar 4 – Mar 18
LettuceSow outdoors · Feb 25 – Mar 11
Carrots, beetsSow outdoors · Mar 4 – Mar 18
TomatoesStart indoors · Jan 28 – Feb 11
TomatoesTransplant · Apr 1 – Apr 15
Peppers, eggplantStart indoors · Jan 14 – Jan 28
Peppers, eggplantTransplant · Apr 8 – Apr 22
BeansSow outdoors · Apr 1 – Apr 15
Sweet cornSow outdoors · Apr 1 – Apr 15
Cucumbers, squashSow outdoors · Apr 1 – Apr 15
Fall lettuce, spinachSow outdoors · Sep 12 – Sep 26
GarlicPlant cloves · Oct 24 – Nov 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 25) and first fall frost (Nov 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 73533 came on Feb 11 — 7 days earlier than the 1991–2020 average (Feb 18).

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 8a in Oklahoma

525 plants native to the lower 48 states, recorded in Oklahoma, and rated by the USDA to survive 10 °F or colder — the bottom of zone 8a. Each links to its USDA PLANTS profile.

Trees 60

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 94

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 189

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 160

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 °FArizona threeawn2 ft · blooms mid summer · high shade tolerance · to −3 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °F

Vines 15

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fcupseed30 ft · blooms late spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °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 Duncan, OK.

Soil in Duncan, OK

The soil mapped at the center of ZIP 73533 is Zaneis — loam, well drained.

TextureLoama good balance for most vegetables
pH6.5neutral; 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: Zaneis-Grainola-Lucien complex, 5 to 12 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 73533; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Duncan, OK

Summer high94 °Faverage high, July
Winter low28 °Faverage low, January
Hot days76days a year at 90 °F or more
Freezing nights69nights a year at 32 °F or less
Growing degree days5,375base 50 °F — the season’s usable heat
Longest day14 h 28 mindaylight on June 21
Shortest day9 h 50 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation37.1 inper year, rain and melted snow
Snowfall3 inper year; 1 days with snow on the ground

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 52 °F, low 28 °F 52°28° JanFebruary: average high 57 °F, low 32 °F 57°32° FebMarch: average high 65 °F, low 41 °F 65°41° MarApril: average high 73 °F, low 49 °F 73°49° AprMay: average high 81 °F, low 59 °F 81°59° MayJune: average high 89 °F, low 68 °F 89°68° JunJuly: average high 94 °F, low 72 °F 94°72° JulAugust: average high 93 °F, low 71 °F 93°71° AugSeptember: average high 86 °F, low 63 °F 86°63° SepOctober: average high 76 °F, low 51 °F 76°51° OctNovember: average high 64 °F, low 39 °F 64°39° NovDecember: average high 54 °F, low 31 °F 54°31° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 1.52 in precipitation, 1.1 in snowfall 1.5❄1 JanFebruary: 1.84 in precipitation, 0.4 in snowfall 1.8 FebMarch: 2.76 in precipitation, 0.2 in snowfall 2.8 MarApril: 3.45 in precipitation 3.5 AprMay: 5.58 in precipitation 5.6 MayJune: 4.49 in precipitation 4.5 JunJuly: 2.58 in precipitation 2.6 JulAugust: 2.90 in precipitation 2.9 AugSeptember: 3.79 in precipitation 3.8 SepOctober: 3.86 in precipitation 3.9 OctNovember: 2.33 in precipitation, 0.3 in snowfall 2.3 NovDecember: 2.04 in precipitation, 0.8 in snowfall 2.0❄1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Duncan, OK (5 mi away); precipitation: Duncan, OK (5 mi away). Daylight is calculated from latitude.

ZIP codes in Duncan

735338a
10 to 15 °F
735348a
10 to 15 °F
735368a
10 to 15 °F

Oklahoma planting zones →

Questions about Duncan

What planting zone is Duncan, OK?

Duncan, OK is in USDA hardiness zone 8a on the 2023 map (8a: 10 to 15 °F).

When is the last frost in Duncan, OK?

The median last spring frost is March 25 and the median first fall frost is November 7 (NOAA 1991–2020 normals, Duncan station).

When can I plant a garden in Duncan, OK?

Cool-season crops like peas and spinach go in around Feb 11 – Mar 4; tomatoes, peppers, beans and squash after about Apr 1, once frost risk has passed.

What kind of onions grow in Duncan, OK?

Intermediate onions: the longest day is 14 h 28 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does Duncan, OK get?

About 37.1 inches of precipitation a year and 3 inches of snowfall (NOAA 1991–2020 normals).