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

Planting zone for 60645 — Chicago, IL

ZIP code 60645 (Chicago, Cook County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 26 and the first fall frost October 21.

Where ZIP 60645 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 26

First frostOct 21

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 Chicago, 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 Chicago, IL

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 26median — 50% chance of a later frost

Safe for tender plantsMay 11only 10% chance of frost after

First fall frostOctober 21median — 10% chance by Oct 5

Growing season176 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 13 and returns around November 1.

From the NOAA station Chicago Botanic Garden, IL — 10 miles away, elevation 630 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 60645

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 15 – Mar 29

SpinachSow outdoors · Mar 15 – Apr 5

Broccoli, cabbageStart indoors · Feb 15 – Mar 1

Broccoli, cabbageTransplant · Apr 5 – Apr 19

Onion setsPlant outdoors · Mar 29 – Apr 12

PotatoesPlant outdoors · Apr 5 – Apr 19

LettuceSow outdoors · Mar 29 – Apr 12

Carrots, beetsSow outdoors · Apr 5 – Apr 19

TomatoesStart indoors · Mar 1 – Mar 15

TomatoesTransplant · May 3 – May 17

Peppers, eggplantStart indoors · Feb 15 – Mar 1

Peppers, eggplantTransplant · May 10 – May 24

BeansSow outdoors · May 3 – May 17

Sweet cornSow outdoors · May 3 – May 17

Cucumbers, squashSow outdoors · May 3 – May 17

Fall lettuce, spinachSow outdoors · Aug 26 – Sep 9

GarlicPlant cloves · Oct 7 – Nov 11

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Oct 21) 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 60645 came on Mar 21 — 15 days earlier than the 1991–2020 average (Apr 5).

average
Apr 52026
Mar 21

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.

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, IL.

Soil in Chicago, IL

The soil mapped at the center of ZIP 60645 is Orthents — loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureLoama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Orthents, loamy, complex, nearly level.

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 60645; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Chicago, IL

Summer high84 °Faverage high, July

Winter low16 °Faverage low, January

Hot days17days a year at 90 °F or more

Freezing nights128nights a year at 32 °F or less

Growing degree days2,963base 50 °F — the season’s usable heat

Longest day15 h 15 mindaylight on June 21

Shortest day9 h 07 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation39.8 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: Chicago Botanic Garden, IL (10 mi away); precipitation: Lincolnwood 1.8 E, IL (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

Lincolnwood, IL · 2 mi

All 80 ZIP codes in Chicago → · Illinois planting zones →

Questions about 60645

What planting zone is ZIP code 60645?

ZIP code 60645 (Chicago, 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 Chicago, IL?

The median last spring frost (32 °F) near 60645 is April 26; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Chicago Botanic Garden station.

When is the first frost in Chicago, IL?

The median first fall frost near 60645 is October 21, giving a median frost-free growing season of 176 days.

When should I plant tomatoes in 60645?

Start tomato seeds indoors around Mar 1 – Mar 15 and set transplants outside around May 3 – May 17, one to three weeks after the median last frost.

How much rain and snow does 60645 get?

About 39.8 inches of precipitation a year (NOAA 1991–2020 normals, Lincolnwood 1.8 E station).

How hot do summers get in Chicago, IL?

The average high peaks at 84 °F in July, with about 17 days a year at 90 °F or more.

What kind of soil does 60645 have?

The USDA soil survey maps Orthents at the center of ZIP 60645: loam, well drained, pH about 6.7 (neutral).

Did spring come early in Chicago, IL in 2026?

Spring leaf-out near 60645 came on Mar 21 in 2026, 15 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Chicago, IL?

Long-day onions: the longest day near 60645 is 15 h 15 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 60645 change?

Yes. The 2012 USDA map put 60645 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.