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

Planting zone for 61920 — Charleston, IL

ZIP code 61920 (Charleston, Coles County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 15 and the first fall frost October 23.

Where ZIP 61920 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostApr 15
First frostOct 23
2012 zone6a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Charleston, 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 Charleston, 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 9
Growing season187 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 2.

From the NOAA station Charleston, IL — 2 miles away, elevation 699 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 61920

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 61920 came on Mar 10 — 13 days earlier than the 1991–2020 average (Mar 23).

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 6a in Illinois

610 plants native to the lower 48 states, recorded in Illinois, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 78

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 108

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 220

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 178

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °F

Vines 9

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °F

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 Charleston, IL.

Soil in Charleston, IL

The soil mapped at the center of ZIP 61920 is Drummer — silty clay loam, poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.7neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter5.5%high
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classPrime farmland if drainedUSDA classification

Map unit: Drummer silty clay 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 61920; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Charleston, IL

Summer high88 °Faverage high, July
Winter low21 °Faverage low, January
Hot days34days a year at 90 °F or more
Freezing nights105nights a year at 32 °F or less
Growing degree days4,056base 50 °F — the season’s usable heat
Longest day14 h 58 mindaylight on June 21
Shortest day9 h 22 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation43.8 inper year, rain and melted snow
Snowfall19 inper year; 28 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 38 °F, low 21 °F 38°21° JanFebruary: average high 43 °F, low 25 °F 43°25° FebMarch: average high 54 °F, low 34 °F 54°34° MarApril: average high 67 °F, low 44 °F 67°44° AprMay: average high 77 °F, low 54 °F 77°54° MayJune: average high 86 °F, low 63 °F 86°63° JunJuly: average high 88 °F, low 66 °F 88°66° JulAugust: average high 87 °F, low 64 °F 87°64° AugSeptember: average high 81 °F, low 57 °F 81°57° SepOctober: average high 69 °F, low 46 °F 69°46° OctNovember: average high 54 °F, low 35 °F 54°35° NovDecember: average high 42 °F, low 26 °F 42°26° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 2.54 in precipitation, 8.1 in snowfall 2.5❄8 JanFebruary: 2.69 in precipitation, 5.5 in snowfall 2.7❄6 FebMarch: 3.11 in precipitation, 1.3 in snowfall 3.1❄1 MarApril: 5.09 in precipitation, 0.3 in snowfall 5.1 AprMay: 4.52 in precipitation 4.5 MayJune: 4.84 in precipitation 4.8 JunJuly: 4.40 in precipitation 4.4 JulAugust: 2.94 in precipitation 2.9 AugSeptember: 3.15 in precipitation 3.1 SepOctober: 3.94 in precipitation 3.9 OctNovember: 3.74 in precipitation, 0.8 in snowfall 3.7❄1 NovDecember: 2.79 in precipitation, 3 in snowfall 2.8❄3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Charleston, IL (2 mi away); precipitation: Charleston, IL (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

619126a
Ashmore, IL · 6 mi
624746a
Westfield, IL · 7 mi
624406a
Lerna, IL · 10 mi
619306a
Hindsboro, IL · 12 mi
619386a
Mattoon, IL · 12 mi
619436a
Oakland, IL · 12 mi
619316a
Humboldt, IL · 12 mi
619106a
Arcola, IL · 13 mi

Illinois planting zones →

Questions about 61920

What planting zone is ZIP code 61920?

ZIP code 61920 (Charleston, IL) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Charleston, IL?

The median last spring frost (32 °F) near 61920 is April 15; after May 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Charleston station.

When is the first frost in Charleston, IL?

The median first fall frost near 61920 is October 23, giving a median frost-free growing season of 187 days.

When should I plant tomatoes in 61920?

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 61920 get?

About 43.8 inches of precipitation a year and 19 inches of snowfall (NOAA 1991–2020 normals, Charleston station).

How hot do summers get in Charleston, IL?

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 61920 have?

The USDA soil survey maps Drummer at the center of ZIP 61920: silty clay loam, poorly drained, pH about 6.7 (neutral).

Did spring come early in Charleston, IL in 2026?

Spring leaf-out near 61920 came on Mar 10 in 2026, 13 days earlier than the 1991–2020 average (Mar 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Charleston, IL?

Intermediate onions: the longest day near 61920 is 14 h 58 min, so day-neutral types bulb best; long-day varieties may not bulb fully.