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

Planting zone for 60180 — Union, IL

ZIP code 60180 (Union, McHenry County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 28 and the first fall frost October 12.

Where ZIP 60180 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostApr 28

First frostOct 12

2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Union, 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 Union, IL

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 28median — 50% chance of a later frost

Safe for tender plantsMay 14only 10% chance of frost after

First fall frostOctober 12median — 10% chance by Sep 28

Growing season166 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 18 and returns around October 25.

From the NOAA station Marengo, IL — 5 miles away, elevation 814 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 60180

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 17 – Mar 31

SpinachSow outdoors · Mar 17 – Apr 7

Broccoli, cabbageStart indoors · Feb 17 – Mar 3

Broccoli, cabbageTransplant · Apr 7 – Apr 21

Onion setsPlant outdoors · Mar 31 – Apr 14

PotatoesPlant outdoors · Apr 7 – Apr 21

LettuceSow outdoors · Mar 31 – Apr 14

Carrots, beetsSow outdoors · Apr 7 – Apr 21

TomatoesStart indoors · Mar 3 – Mar 17

TomatoesTransplant · May 5 – May 19

Peppers, eggplantStart indoors · Feb 17 – Mar 3

Peppers, eggplantTransplant · May 12 – May 26

BeansSow outdoors · May 5 – May 19

Sweet cornSow outdoors · May 5 – May 19

Cucumbers, squashSow outdoors · May 5 – May 19

Fall lettuce, spinachSow outdoors · Aug 17 – Aug 31

GarlicPlant cloves · Sep 28 – Nov 2

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 12) 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 60180 came on Mar 28 — 12 days earlier than the 1991–2020 average (Apr 9).

average
Apr 92026
Mar 28

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 5b in Illinois

584 plants native to the lower 48 states, recorded in Illinois, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. 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 Union, IL.

Soil in Union, IL

The soil mapped at the center of ZIP 60180 is Lisbon — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables

pH6.5neutral; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter4%moderate

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classprime farmlandUSDA classification

Map unit: Lisbon 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 60180; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Union, IL

Summer high84 °Faverage high, July

Winter low13 °Faverage low, January

Hot days15days a year at 90 °F or more

Freezing nights147nights a year at 32 °F or less

Growing degree days2,850base 50 °F — the season’s usable heat

Longest day15 h 16 mindaylight on June 21

Shortest day9 h 05 mindaylight on December 21

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

Precipitation37.6 inper year, rain and melted snow

Snowfall31 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Marengo, IL (5 mi away); precipitation: Marengo, IL (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

Crystal Lake, IL · 8 mi

600145b

Crystal Lake, IL · 10 mi

601405b

Hampshire, IL · 10 mi

601565b

Lake In The Hills, IL · 10 mi

601365b

Gilberts, IL · 11 mi

Illinois planting zones →

Questions about 60180

What planting zone is ZIP code 60180?

ZIP code 60180 (Union, IL) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Union, IL?

The median last spring frost (32 °F) near 60180 is April 28; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Marengo station.

When is the first frost in Union, IL?

The median first fall frost near 60180 is October 12, giving a median frost-free growing season of 166 days.

When should I plant tomatoes in 60180?

Start tomato seeds indoors around Mar 3 – Mar 17 and set transplants outside around May 5 – May 19, one to three weeks after the median last frost.

How much rain and snow does 60180 get?

About 37.6 inches of precipitation a year and 31 inches of snowfall (NOAA 1991–2020 normals, Marengo station).

How hot do summers get in Union, IL?

The average high peaks at 84 °F in July, with about 15 days a year at 90 °F or more.

What kind of soil does 60180 have?

The USDA soil survey maps Lisbon at the center of ZIP 60180: silt loam, somewhat poorly drained, pH about 6.5 (neutral).

Did spring come early in Union, IL in 2026?

Spring leaf-out near 60180 came on Mar 28 in 2026, 12 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Union, IL?

Long-day onions: the longest day near 60180 is 15 h 16 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).