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

Planting zone for 60527 — Willowbrook, IL

ZIP code 60527 (Willowbrook, DuPage County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 19 and the first fall frost October 22.

Where ZIP 60527 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 19
First frostOct 22
2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Willowbrook, 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 Willowbrook, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 19median — 50% chance of a later frost
Safe for tender plantsMay 5only 10% chance of frost after
First fall frostOctober 22median — 10% chance by Oct 8
Growing season183 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 7 and returns around November 1.

From the NOAA station Little Red School Hse, IL — 4 miles away, elevation 715 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 60527

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 8 – Mar 22
SpinachSow outdoors · Mar 8 – Mar 29
Broccoli, cabbageStart indoors · Feb 8 – Feb 22
Broccoli, cabbageTransplant · Mar 29 – Apr 12
Onion setsPlant outdoors · Mar 22 – Apr 5
PotatoesPlant outdoors · Mar 29 – Apr 12
LettuceSow outdoors · Mar 22 – Apr 5
Carrots, beetsSow outdoors · Mar 29 – Apr 12
TomatoesStart indoors · Feb 22 – Mar 8
TomatoesTransplant · Apr 26 – May 10
Peppers, eggplantStart indoors · Feb 8 – Feb 22
Peppers, eggplantTransplant · May 3 – May 17
BeansSow outdoors · Apr 26 – May 10
Sweet cornSow outdoors · Apr 26 – May 10
Cucumbers, squashSow outdoors · Apr 26 – May 10
Fall lettuce, spinachSow outdoors · Aug 27 – Sep 10
GarlicPlant cloves · Oct 8 – Nov 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 19) and first fall frost (Oct 22) 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 60527 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 Willowbrook, IL.

Soil in Willowbrook, IL

The soil mapped at the center of ZIP 60527 is Elliott — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables
pH6.8neutral; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter4.3%moderate
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classprime farmlandUSDA classification

Map unit: Elliott 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 60527; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Willowbrook, IL

Summer high90 °Faverage high, July
Winter low15 °Faverage low, January
Hot days45days a year at 90 °F or more
Freezing nights131nights a year at 32 °F or less
Growing degree days3,512base 50 °F — the season’s usable heat
Longest day15 h 13 mindaylight on June 21
Shortest day9 h 08 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation40.4 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 33 °F, low 15 °F 33°15° JanFebruary: average high 37 °F, low 18 °F 37°18° FebMarch: average high 49 °F, low 28 °F 49°28° MarApril: average high 62 °F, low 39 °F 62°39° AprMay: average high 73 °F, low 50 °F 73°50° MayJune: average high 84 °F, low 60 °F 84°60° JunJuly: average high 90 °F, low 64 °F 90°64° JulAugust: average high 87 °F, low 63 °F 87°63° AugSeptember: average high 80 °F, low 55 °F 80°55° SepOctober: average high 65 °F, low 43 °F 65°43° OctNovember: average high 50 °F, low 31 °F 50°31° NovDecember: average high 38 °F, low 21 °F 38°21° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.23 in precipitation 2.2 JanFebruary: 2.06 in precipitation 2.1 FebMarch: 2.50 in precipitation 2.5 MarApril: 3.78 in precipitation 3.8 AprMay: 4.85 in precipitation 4.8 MayJune: 4.58 in precipitation 4.6 JunJuly: 4.16 in precipitation 4.2 JulAugust: 4.28 in precipitation 4.3 AugSeptember: 3.36 in precipitation 3.4 SepOctober: 3.64 in precipitation 3.6 OctNovember: 2.71 in precipitation 2.7 NovDecember: 2.27 in precipitation 2.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Little Red School Hse, IL (4 mi away); precipitation: Burr Ridge 1.9 Sw, IL (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

605616a
Darien, IL · 3 mi
604806a
Willow Springs, IL · 3 mi
605216a
Hinsdale, IL · 4 mi
605146a
Clarendon Hills, IL · 4 mi
605596a
Westmont, IL · 4 mi
605256a
La Grange, IL · 4 mi
605586a
Western Springs, IL · 4 mi
605165b
Downers Grove, IL · 5 mi

Illinois planting zones →

Questions about 60527

What planting zone is ZIP code 60527?

ZIP code 60527 (Willowbrook, 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 Willowbrook, IL?

The median last spring frost (32 °F) near 60527 is April 19; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Little Red School Hse station.

When is the first frost in Willowbrook, IL?

The median first fall frost near 60527 is October 22, giving a median frost-free growing season of 183 days.

When should I plant tomatoes in 60527?

Start tomato seeds indoors around Feb 22 – Mar 8 and set transplants outside around Apr 26 – May 10, one to three weeks after the median last frost.

How much rain and snow does 60527 get?

About 40.4 inches of precipitation a year (NOAA 1991–2020 normals, Burr Ridge 1.9 Sw station).

How hot do summers get in Willowbrook, IL?

The average high peaks at 90 °F in July, with about 45 days a year at 90 °F or more.

What kind of soil does 60527 have?

The USDA soil survey maps Elliott at the center of ZIP 60527: silt loam, somewhat poorly drained, pH about 6.8 (neutral).

Did spring come early in Willowbrook, IL in 2026?

Spring leaf-out near 60527 came on Mar 21 in 2026, 14 days earlier than the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Willowbrook, IL?

Long-day onions: the longest day near 60527 is 15 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 60527 change?

Yes. The 2012 USDA map put 60527 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.