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

Planting zone for 62239 — Dupo, IL

ZIP code 62239 (Dupo, St. Clair County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 8 and the first fall frost October 26.

Where ZIP 62239 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 8

First frostOct 26

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 Dupo, IL…

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 Dupo, IL

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 23only 10% chance of frost after

First fall frostOctober 26median — 10% chance by Oct 12

Growing season200 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 28 and returns around November 6.

From the NOAA station Cahokia St Louis Airport, IL — 3 miles away, elevation 413 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 62239

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 31 – Sep 14

GarlicPlant cloves · Oct 12 – Nov 16

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 8) and first fall frost (Oct 26) 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 62239 came on Mar 6 — 7 days earlier than the 1991–2020 average (Mar 13).

average
Mar 132026
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 7a in Illinois

633 plants native to the lower 48 states, recorded in Illinois, 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 Dupo, IL.

Soil in Dupo, IL

The soil mapped at the center of ZIP 62239 is Menfro — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.2slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Menfro silt loam, karst, 12 to 25 percent slopes, severely 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 62239; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dupo, IL

Summer high89 °Faverage high, July

Winter low24 °Faverage low, January

Hot days46days a year at 90 °F or more

Freezing nights98nights a year at 32 °F or less

Growing degree days4,263base 50 °F — the season’s usable heat

Longest day14 h 51 mindaylight on June 21

Shortest day9 h 28 mindaylight on December 21

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

Precipitation40.8 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: Cahokia St Louis Airport, IL (3 mi away); precipitation: Cahokia St Louis Airport, IL (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

622407a

East Carondelet, IL · 2 mi

622067a

East Saint Louis, IL · 3 mi

622077a

East Saint Louis, IL · 4 mi

622237a

Belleville, IL · 5 mi

622607a

Millstadt, IL · 5 mi

631117a

Saint Louis, MO · 6 mi

622057a

East Saint Louis, IL · 6 mi

631187a

Saint Louis, MO · 6 mi

Illinois planting zones →

Questions about 62239

What planting zone is ZIP code 62239?

ZIP code 62239 (Dupo, IL) 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 Dupo, IL?

The median last spring frost (32 °F) near 62239 is April 8; after April 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cahokia St Louis Airport station.

When is the first frost in Dupo, IL?

The median first fall frost near 62239 is October 26, giving a median frost-free growing season of 200 days.

When should I plant tomatoes in 62239?

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 62239 get?

About 40.8 inches of precipitation a year (NOAA 1991–2020 normals, Cahokia St Louis Airport station).

How hot do summers get in Dupo, IL?

The average high peaks at 89 °F in July, with about 46 days a year at 90 °F or more.

What kind of soil does 62239 have?

The USDA soil survey maps Menfro at the center of ZIP 62239: silt loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Dupo, IL in 2026?

Spring leaf-out near 62239 came on Mar 6 in 2026, 7 days earlier than the 1991–2020 average (Mar 13), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Dupo, IL?

Intermediate onions: the longest day near 62239 is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 62239 change?

Yes. The 2012 USDA map put 62239 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.