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

Planting zone for 63045 — Earth City, MO

ZIP code 63045 (Earth City, St. Louis 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 29.

Where ZIP 63045 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 29

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 Earth City, 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 Earth City, 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 24only 10% chance of frost after

First fall frostOctober 29median — 10% chance by Oct 16

Growing season203 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 30 and returns around November 10.

From the NOAA station St Charles Elm Pt, MO — 4 miles away, elevation 472 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 63045

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 · Sep 3 – Sep 17

GarlicPlant cloves · Oct 15 – Nov 19

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 8) and first fall frost (Oct 29) 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 63045 came on Mar 3 — 13 days earlier than the 1991–2020 average (Mar 16).

average
Mar 162026
Mar 3

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 Earth City, MO

The soil mapped at the center of ZIP 63045 is Fishpot — silt loam, somewhat poorly drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureSilt loama good balance for most vegetables

pH5.7moderately acidic; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Fishpot complex, 0 to 2 percent slopes, occasionally flooded.

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 63045; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Earth City, MO

Summer high88 °Faverage high, July

Winter low22 °Faverage low, January

Hot days34days a year at 90 °F or more

Freezing nights105nights a year at 32 °F or less

Growing degree days4,108base 50 °F — the season’s usable heat

Longest day14 h 53 mindaylight on June 21

Shortest day9 h 27 mindaylight on December 21

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

Precipitation45.7 inper year, rain and melted snow

Snowfall9 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: St Charles Elm Pt, MO (4 mi away); precipitation: St Charles Elm Pt, MO (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

6 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

633027a

Saint Charles, MO · 1 mi

630446b

Bridgeton, MO · 2 mi

630437a

Maryland Heights, MO · 3 mi

Saint Charles, MO · 5 mi

631467a

Saint Louis, MO · 5 mi

630747a

Saint Ann, MO · 5 mi

Missouri planting zones →

Questions about 63045

What planting zone is ZIP code 63045?

ZIP code 63045 (Earth City, 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 Earth City, MO?

The median last spring frost (32 °F) near 63045 is April 8; after April 24 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, St Charles Elm Pt station.

When is the first frost in Earth City, MO?

The median first fall frost near 63045 is October 29, giving a median frost-free growing season of 203 days.

When should I plant tomatoes in 63045?

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 63045 get?

About 45.7 inches of precipitation a year and 9 inches of snowfall (NOAA 1991–2020 normals, St Charles Elm Pt station).

How hot do summers get in Earth City, MO?

The average high peaks at 88 °F in July, with about 34 days a year at 90 °F or more.

What kind of soil does 63045 have?

The USDA soil survey maps Fishpot at the center of ZIP 63045: silt loam, somewhat poorly drained, pH about 5.7 (moderately acidic).

Did spring come early in Earth City, MO in 2026?

Spring leaf-out near 63045 came on Mar 3 in 2026, 13 days earlier than the 1991–2020 average (Mar 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Earth City, MO?

Intermediate onions: the longest day near 63045 is 14 h 53 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 63045 change?

Yes. The 2012 USDA map put 63045 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.