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

Planting zone for 63039 — Gray Summit, MO

ZIP code 63039 (Gray Summit, Franklin County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 8 and the first fall frost October 25.

Where ZIP 63039 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 8

First frostOct 25

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Gray Summit, MO…

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 Gray Summit, MO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 8median — 50% chance of a later frost

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

First fall frostOctober 25median — 10% chance by Oct 13

Growing season199 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 29 and returns around November 4.

From the NOAA station Washington, MO — 8 miles away, elevation 486 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 63039

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 25 – Mar 11

SpinachSow outdoors · Feb 25 – Mar 18

Broccoli, cabbageStart indoors · Jan 28 – Feb 11

Broccoli, cabbageTransplant · Mar 18 – Apr 1

Onion setsPlant outdoors · Mar 11 – Mar 25

PotatoesPlant outdoors · Mar 18 – Apr 1

LettuceSow outdoors · Mar 11 – Mar 25

Carrots, beetsSow outdoors · Mar 18 – Apr 1

TomatoesStart indoors · Feb 11 – Feb 25

TomatoesTransplant · Apr 15 – Apr 29

Peppers, eggplantStart indoors · Jan 28 – Feb 11

Peppers, eggplantTransplant · Apr 22 – May 6

BeansSow outdoors · Apr 15 – Apr 29

Sweet cornSow outdoors · Apr 15 – Apr 29

Cucumbers, squashSow outdoors · Apr 15 – Apr 29

Fall lettuce, spinachSow outdoors · Aug 30 – Sep 13

GarlicPlant cloves · Oct 11 – Nov 15

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 8) and first fall frost (Oct 25) 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 63039 came on Mar 6 — 9 days earlier than the 1991–2020 average (Mar 15).

average
Mar 152026
Mar 6

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 Missouri

525 plants native to the lower 48 states, recorded in Missouri, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Gray Summit, MO.

Soil in Gray Summit, MO

The soil mapped at the center of ZIP 63039 is Wrengart — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables

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

DrainageModerately well drainednatural drainage class

Organic matter2.2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Wrengart silt loam, 8 to 15 percent slopes, eroded.

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 63039; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Gray Summit, MO

Summer high88 °Faverage high, July

Winter low20 °Faverage low, January

Hot days40days a year at 90 °F or more

Freezing nights116nights a year at 32 °F or less

Growing degree days3,948base 50 °F — the season’s usable heat

Longest day14 h 51 mindaylight on June 21

Shortest day9 h 29 mindaylight on December 21

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

Precipitation43 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Washington, MO (8 mi away); precipitation: Pacific 2.4 Wnw, MO (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

630556b

Labadie, MO · 3 mi

630896b

Villa Ridge, MO · 3 mi

630696b

Pacific, MO · 7 mi

630736b

Saint Albans, MO · 8 mi

Robertsville, MO · 9 mi

630846b

Union, MO · 11 mi

Missouri planting zones →

Questions about 63039

What planting zone is ZIP code 63039?

ZIP code 63039 (Gray Summit, MO) 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 Gray Summit, MO?

The median last spring frost (32 °F) near 63039 is April 8; after April 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Washington station.

When is the first frost in Gray Summit, MO?

The median first fall frost near 63039 is October 25, giving a median frost-free growing season of 199 days.

When should I plant tomatoes in 63039?

Start tomato seeds indoors around Feb 11 – Feb 25 and set transplants outside around Apr 15 – Apr 29, one to three weeks after the median last frost.

How much rain and snow does 63039 get?

About 43 inches of precipitation a year (NOAA 1991–2020 normals, Pacific 2.4 Wnw station).

How hot do summers get in Gray Summit, MO?

The average high peaks at 88 °F in July, with about 40 days a year at 90 °F or more.

What kind of soil does 63039 have?

The USDA soil survey maps Wrengart at the center of ZIP 63039: silt loam, moderately well drained, pH about 5.6 (moderately acidic).

Did spring come early in Gray Summit, MO in 2026?

Spring leaf-out near 63039 came on Mar 6 in 2026, 9 days earlier than the 1991–2020 average (Mar 15), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Gray Summit, MO?

Intermediate onions: the longest day near 63039 is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 63039 change?

Yes. The 2012 USDA map put 63039 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.