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

Planting zone for 62421 — Claremont, IL

ZIP code 62421 (Claremont, Richland County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 15 and the first fall frost October 23.

Where ZIP 62421 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 15

First frostOct 23

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 Claremont, 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 Claremont, IL

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 15median — 50% chance of a later frost

Safe for tender plantsMay 3only 10% chance of frost after

First fall frostOctober 23median — 10% chance by Oct 8

Growing season189 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 1.

From the NOAA station Olney 2s, IL — 8 miles away, elevation 459 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 62421

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 4 – Mar 18

SpinachSow outdoors · Mar 4 – Mar 25

Broccoli, cabbageStart indoors · Feb 4 – Feb 18

Broccoli, cabbageTransplant · Mar 25 – Apr 8

Onion setsPlant outdoors · Mar 18 – Apr 1

PotatoesPlant outdoors · Mar 25 – Apr 8

LettuceSow outdoors · Mar 18 – Apr 1

Carrots, beetsSow outdoors · Mar 25 – Apr 8

TomatoesStart indoors · Feb 18 – Mar 4

TomatoesTransplant · Apr 22 – May 6

Peppers, eggplantStart indoors · Feb 4 – Feb 18

Peppers, eggplantTransplant · Apr 29 – May 13

BeansSow outdoors · Apr 22 – May 6

Sweet cornSow outdoors · Apr 22 – May 6

Cucumbers, squashSow outdoors · Apr 22 – May 6

Fall lettuce, spinachSow outdoors · Aug 28 – Sep 11

GarlicPlant cloves · Oct 9 – Nov 13

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 15) and first fall frost (Oct 23) 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 62421 came on Mar 8 — 11 days earlier than the 1991–2020 average (Mar 19).

average
Mar 192026
Mar 8

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 Illinois

620 plants native to the lower 48 states, recorded in Illinois, 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 Claremont, IL.

Soil in Claremont, IL

The soil mapped at the center of ZIP 62421 is Huey — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter1.75%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Huey silt loam, 0 to 2 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 62421; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Claremont, IL

Summer high87 °Faverage high, July

Winter low21 °Faverage low, January

Hot days32days a year at 90 °F or more

Freezing nights105nights a year at 32 °F or less

Growing degree days3,829base 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

Precipitation48.8 inper year, rain and melted snow

Snowfall11 inper year; 14 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: Olney 2s, IL (8 mi away); precipitation: Olney 2s, IL (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

Bridgeport, IL · 10 mi

624256b

Dundas, IL · 10 mi

624756b

West Liberty, IL · 11 mi

624526b

Parkersburg, IL · 12 mi

624596b

Sainte Marie, IL · 13 mi

Illinois planting zones →

Questions about 62421

What planting zone is ZIP code 62421?

ZIP code 62421 (Claremont, IL) 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 Claremont, IL?

The median last spring frost (32 °F) near 62421 is April 15; after May 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Olney 2s station.

When is the first frost in Claremont, IL?

The median first fall frost near 62421 is October 23, giving a median frost-free growing season of 189 days.

When should I plant tomatoes in 62421?

Start tomato seeds indoors around Feb 18 – Mar 4 and set transplants outside around Apr 22 – May 6, one to three weeks after the median last frost.

How much rain and snow does 62421 get?

About 48.8 inches of precipitation a year and 11 inches of snowfall (NOAA 1991–2020 normals, Olney 2s station).

How hot do summers get in Claremont, IL?

The average high peaks at 87 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 62421 have?

The USDA soil survey maps Huey at the center of ZIP 62421: silt loam, poorly drained, pH about 7.0 (neutral).

Did spring come early in Claremont, IL in 2026?

Spring leaf-out near 62421 came on Mar 8 in 2026, 11 days earlier than the 1991–2020 average (Mar 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Claremont, IL?

Intermediate onions: the longest day near 62421 is 14 h 53 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 62421 change?

Yes. The 2012 USDA map put 62421 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.