Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 66770 — Riverton, KS

ZIP code 66770 (Riverton, Cherokee County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 5 and the first fall frost October 31.

Where ZIP 66770 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 5

First frostOct 31

2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Riverton, 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 Riverton, KS

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 5median — 50% chance of a later frost

Safe for tender plantsApril 22only 10% chance of frost after

First fall frostOctober 31median — 10% chance by Oct 18

Growing season208 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 25 and returns around November 9.

From the NOAA station Columbus, KS — 10 miles away, elevation 892 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 66770

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 22 – Mar 8

SpinachSow outdoors · Feb 22 – Mar 15

Broccoli, cabbageStart indoors · Jan 25 – Feb 8

Broccoli, cabbageTransplant · Mar 15 – Mar 29

Onion setsPlant outdoors · Mar 8 – Mar 22

PotatoesPlant outdoors · Mar 15 – Mar 29

LettuceSow outdoors · Mar 8 – Mar 22

Carrots, beetsSow outdoors · Mar 15 – Mar 29

TomatoesStart indoors · Feb 8 – Feb 22

TomatoesTransplant · Apr 12 – Apr 26

Peppers, eggplantStart indoors · Jan 25 – Feb 8

Peppers, eggplantTransplant · Apr 19 – May 3

BeansSow outdoors · Apr 12 – Apr 26

Sweet cornSow outdoors · Apr 12 – Apr 26

Cucumbers, squashSow outdoors · Apr 12 – Apr 26

Fall lettuce, spinachSow outdoors · Sep 5 – Sep 19

GarlicPlant cloves · Oct 17 – Nov 21

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 5) and first fall frost (Oct 31) 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 66770 came on Feb 16 — 16 days earlier than the 1991–2020 average (Mar 4).

average
Mar 42026
Feb 16

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 7a in Kansas

439 plants native to the lower 48 states, recorded in Kansas, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

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 Riverton, KS.

Soil in Riverton, KS

The soil mapped at the center of ZIP 66770 is Dennis — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables

pH5.6moderately acidic; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter2.5%moderate

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classprime farmlandUSDA classification

Map unit: Dennis silt loam, 1 to 3 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 66770; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Riverton, KS

Summer high90 °Faverage high, July

Winter low23 °Faverage low, January

Hot days46days a year at 90 °F or more

Freezing nights95nights a year at 32 °F or less

Growing degree days4,409base 50 °F — the season’s usable heat

Longest day14 h 43 mindaylight on June 21

Shortest day9 h 37 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation46 inper year, rain and melted snow

Snowfall7 inper year; 8 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Columbus, KS (10 mi away); precipitation: Columbus, KS (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

667397a

Galena, KS · 5 mi

667137a

Baxter Springs, KS · 5 mi

Carl Junction, MO · 11 mi

648027a

Joplin, MO · 11 mi

Kansas planting zones →

Questions about 66770

What planting zone is ZIP code 66770?

ZIP code 66770 (Riverton, KS) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Riverton, KS?

The median last spring frost (32 °F) near 66770 is April 5; after April 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Columbus station.

When is the first frost in Riverton, KS?

The median first fall frost near 66770 is October 31, giving a median frost-free growing season of 208 days.

When should I plant tomatoes in 66770?

Start tomato seeds indoors around Feb 8 – Feb 22 and set transplants outside around Apr 12 – Apr 26, one to three weeks after the median last frost.

How much rain and snow does 66770 get?

About 46 inches of precipitation a year and 7 inches of snowfall (NOAA 1991–2020 normals, Columbus station).

How hot do summers get in Riverton, KS?

The average high peaks at 90 °F in July, with about 46 days a year at 90 °F or more.

What kind of soil does 66770 have?

The USDA soil survey maps Dennis at the center of ZIP 66770: silt loam, somewhat poorly drained, pH about 5.6 (moderately acidic).

Did spring come early in Riverton, KS in 2026?

Spring leaf-out near 66770 came on Feb 16 in 2026, 16 days earlier than the 1991–2020 average (Mar 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Riverton, KS?

Intermediate onions: the longest day near 66770 is 14 h 43 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 66770 change?

Yes. The 2012 USDA map put 66770 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.