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

Planting zone for 67644 — Kirwin, KS

ZIP code 67644 (Kirwin, Phillips County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 30 and the first fall frost October 7.

Where ZIP 67644 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostApr 30
First frostOct 7
2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kirwin, KS…

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 Kirwin, KS

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 30median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 7median — 10% chance by Sep 24
Growing season159 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 20 and returns around October 15.

From the NOAA station Kirwin Dam, KS — 2 miles away, elevation 1,696 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 67644

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 19 – Apr 2
SpinachSow outdoors · Mar 19 – Apr 9
Broccoli, cabbageStart indoors · Feb 19 – Mar 5
Broccoli, cabbageTransplant · Apr 9 – Apr 23
Onion setsPlant outdoors · Apr 2 – Apr 16
PotatoesPlant outdoors · Apr 9 – Apr 23
LettuceSow outdoors · Apr 2 – Apr 16
Carrots, beetsSow outdoors · Apr 9 – Apr 23
TomatoesStart indoors · Mar 5 – Mar 19
TomatoesTransplant · May 7 – May 21
Peppers, eggplantStart indoors · Feb 19 – Mar 5
Peppers, eggplantTransplant · May 14 – May 28
BeansSow outdoors · May 7 – May 21
Sweet cornSow outdoors · May 7 – May 21
Cucumbers, squashSow outdoors · May 7 – May 21
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 (Apr 30) 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 67644 came on Mar 1 — 21 days earlier than the 1991–2020 average (Mar 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 Kirwin, KS

The soil mapped at the center of ZIP 67644 is Brownell — gravelly loam, well drained.

TextureGravelly loama good balance for most vegetables
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Brownell-Heizer gravelly loams, 3 to 30 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 67644; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kirwin, KS

Summer high92 °Faverage high, July
Winter low13 °Faverage low, January
Hot days67days a year at 90 °F or more
Freezing nights158nights a year at 32 °F or less
Growing degree days3,592base 50 °F — the season’s usable heat
Longest day14 h 59 mindaylight on June 21
Shortest day9 h 22 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation25.7 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 40 °F, low 13 °F 40°13° JanFebruary: average high 45 °F, low 16 °F 45°16° FebMarch: average high 56 °F, low 25 °F 56°25° MarApril: average high 66 °F, low 35 °F 66°35° AprMay: average high 75 °F, low 48 °F 75°48° MayJune: average high 87 °F, low 60 °F 87°60° JunJuly: average high 92 °F, low 65 °F 92°65° JulAugust: average high 90 °F, low 61 °F 90°61° AugSeptember: average high 82 °F, low 52 °F 82°52° SepOctober: average high 69 °F, low 37 °F 69°37° OctNovember: average high 54 °F, low 25 °F 54°25° NovDecember: average high 42 °F, low 16 °F 42°16° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 0.53 in precipitation 0.5 JanFebruary: 0.76 in precipitation 0.8 FebMarch: 1.40 in precipitation 1.4 MarApril: 2.24 in precipitation 2.2 AprMay: 4.19 in precipitation 4.2 MayJune: 3.29 in precipitation 3.3 JunJuly: 3.96 in precipitation 4.0 JulAugust: 3.35 in precipitation 3.4 AugSeptember: 2.17 in precipitation 2.2 SepOctober: 1.88 in precipitation 1.9 OctNovember: 1.06 in precipitation 1.1 NovDecember: 0.85 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Kirwin Dam, KS (2 mi away); precipitation: Kirwin Dam, KS (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

676286a
Cedar, KS · 8 mi
676396a
Glade, KS · 9 mi
676216a
Agra, KS · 13 mi
669326a
Athol, KS · 15 mi
676386a
Gaylord, KS · 16 mi
676616a
Phillipsburg, KS · 16 mi
676756a
Woodston, KS · 16 mi
676696a
Stockton, KS · 16 mi

Kansas planting zones →

Questions about 67644

What planting zone is ZIP code 67644?

ZIP code 67644 (Kirwin, KS) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Kirwin, KS?

The median last spring frost (32 °F) near 67644 is April 30; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Kirwin Dam station.

When is the first frost in Kirwin, KS?

The median first fall frost near 67644 is October 7, giving a median frost-free growing season of 159 days.

When should I plant tomatoes in 67644?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 67644 get?

About 25.7 inches of precipitation a year (NOAA 1991–2020 normals, Kirwin Dam station).

How hot do summers get in Kirwin, KS?

The average high peaks at 92 °F in July, with about 67 days a year at 90 °F or more.

What kind of soil does 67644 have?

The USDA soil survey maps Brownell at the center of ZIP 67644: gravelly loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Kirwin, KS in 2026?

Spring leaf-out near 67644 came on Mar 1 in 2026, 21 days earlier than the 1991–2020 average (Mar 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Kirwin, KS?

Intermediate onions: the longest day near 67644 is 14 h 59 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 67644 change?

Yes. The 2012 USDA map put 67644 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.