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

Planting zone for Chicago Heights, IL

Chicago Heights, IL is in USDA zone 6a across its 2 ZIP codes. The median last spring frost is April 23 and the first fall frost October 20.

Chicago Heights on the zone map

Outlined: its 1 ZIP code areas · 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
ZIP codes2
Last frostApr 23
First frostOct 20
Growing season179 days

6a 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Chicago Heights, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 23median — 50% chance of a later frost
Safe for tender plantsMay 11only 10% chance of frost after
First fall frostOctober 20median — 10% chance by Oct 6
Growing season179 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around October 30.

From the NOAA station Park Forest, IL, elevation 709 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 Chicago Heights

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 12 – Mar 26
SpinachSow outdoors · Mar 12 – Apr 2
Broccoli, cabbageStart indoors · Feb 12 – Feb 26
Broccoli, cabbageTransplant · Apr 2 – Apr 16
Onion setsPlant outdoors · Mar 26 – Apr 9
PotatoesPlant outdoors · Apr 2 – Apr 16
LettuceSow outdoors · Mar 26 – Apr 9
Carrots, beetsSow outdoors · Apr 2 – Apr 16
TomatoesStart indoors · Feb 26 – Mar 12
TomatoesTransplant · Apr 30 – May 14
Peppers, eggplantStart indoors · Feb 12 – Feb 26
Peppers, eggplantTransplant · May 7 – May 21
BeansSow outdoors · Apr 30 – May 14
Sweet cornSow outdoors · Apr 30 – May 14
Cucumbers, squashSow outdoors · Apr 30 – May 14
Fall lettuce, spinachSow outdoors · Aug 25 – Sep 8
GarlicPlant cloves · Oct 6 – Nov 10
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 20) 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 60411 came on Mar 21 — 14 days earlier than the 1991–2020 average (Apr 4).

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 Chicago Heights, IL.

Soil in Chicago Heights, IL

The soil mapped at the center of ZIP 60411 is Milford — silty clay loam, poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter5.25%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Milford-Martinton complex, 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 60411; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Chicago Heights, IL

Summer high84 °Faverage high, July
Winter low15 °Faverage low, January
Hot days16days a year at 90 °F or more
Freezing nights126nights a year at 32 °F or less
Growing degree days3,114base 50 °F — the season’s usable heat
Longest day15 h 11 mindaylight on June 21
Shortest day9 h 10 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation40.9 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 31 °F, low 15 °F 31°15° JanFebruary: average high 35 °F, low 18 °F 35°18° FebMarch: average high 46 °F, low 28 °F 46°28° MarApril: average high 59 °F, low 38 °F 59°38° AprMay: average high 71 °F, low 49 °F 71°49° MayJune: average high 80 °F, low 59 °F 80°59° JunJuly: average high 84 °F, low 64 °F 84°64° JulAugust: average high 82 °F, low 62 °F 82°62° AugSeptember: average high 76 °F, low 55 °F 76°55° SepOctober: average high 63 °F, low 42 °F 63°42° OctNovember: average high 48 °F, low 31 °F 48°31° NovDecember: average high 36 °F, low 22 °F 36°22° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.36 in precipitation 2.4 JanFebruary: 2.11 in precipitation 2.1 FebMarch: 2.46 in precipitation 2.5 MarApril: 3.87 in precipitation 3.9 AprMay: 4.37 in precipitation 4.4 MayJune: 4.83 in precipitation 4.8 JunJuly: 4.39 in precipitation 4.4 JulAugust: 4.16 in precipitation 4.2 AugSeptember: 3.41 in precipitation 3.4 SepOctober: 3.66 in precipitation 3.7 OctNovember: 2.95 in precipitation 3.0 NovDecember: 2.28 in precipitation 2.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Park Forest, IL (5 mi away); precipitation: Dyer 1.0 Wnw, IN (3 mi away). Daylight is calculated from latitude.

ZIP codes in Chicago Heights

604116a
−10 to −5 °F
604126a
−10 to −5 °F

Illinois planting zones →

Questions about Chicago Heights

What planting zone is Chicago Heights, IL?

Chicago Heights, IL is in USDA hardiness zone 6a on the 2023 map (6a: −10 to −5 °F).

When is the last frost in Chicago Heights, IL?

The median last spring frost is April 23 and the median first fall frost is October 20 (NOAA 1991–2020 normals, Park Forest station).

When can I plant a garden in Chicago Heights, IL?

Cool-season crops like peas and spinach go in around Mar 12 – Apr 2; tomatoes, peppers, beans and squash after about Apr 30, once frost risk has passed.

What kind of onions grow in Chicago Heights, IL?

Long-day onions: the longest day is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Chicago Heights, IL get?

About 40.9 inches of precipitation a year (NOAA 1991–2020 normals).