What Hardiness Zone Is Illinois?

USDA 2023 Plant Hardiness Zone Map · 1,545 ZIP codes · Data updated 2026-10-28

Quick answer

Illinois spans USDA hardiness zones 5a–7a on the 2023 Plant Hardiness Zone Map. The most common zone is 6a, covering 42% of Illinois's ZIP codes, followed by zone 5b (29%). Zone 6a means the coldest night of an average winter reaches −10°F to −5°F (−23°C to −21°C). Enter your ZIP code for your exact zone.

Illinois hardiness zones by share of ZIP codes

Zone 5a2% · 28 ZIPs

Zone 5b29% · 447 ZIPs

Zone 6a42% · 646 ZIPs

Zone 6b17% · 260 ZIPs

Zone 7a11% · 164 ZIPs

What the zones mean for Illinois gardeners

Coldest and warmest towns: among towns with NOAA weather stations, Stockton 3 NNE (970 ft) is in zone 5a, while Cairo 3N (313 ft) is in zone 7a. That is a difference of about 20°F in the coldest night of a typical winter.
Same zone, different frost dates: within zone 6a, the median last spring frost ranges from April 8 at Gladstone Dam 18 to April 30 at Waukegan, 22 days apart. Your zone tells you which perennials survive winter; your frost dates tell you when to plant.

Typical frost dates in each Illinois zone

Medians across NOAA weather stations in each zone. Colder zones usually have later spring frosts, but local terrain can shift the dates by weeks.

Zone	Last spring frost	First fall frost	Stations
5a	April 27	October 9	5
5b	April 24	October 17	55
6a	April 17	October 21	58
6b	April 11	October 24	31
7a	April 7	October 26	19

Hardiness zones for Illinois cities

Zones at the National Weather Service stations, mostly city airports, with their median frost dates.


Belleville Siu Rsch	6b	−5°F to 0°F	450	Apr 12	Oct 20
Cahokia St Louis Airport	7a	0°F to 5°F	413	Apr 8	Oct 26
Cairo 3N	7a	0°F to 5°F	313	Apr 2	Oct 31
Carbondale Southern Il Airport	7a	0°F to 5°F	406	Apr 9	Oct 22
Champaign 9 SW	6a	−10°F to −5°F	700	Apr 23	Oct 13
Champaign Willard Airport	6a	−10°F to −5°F	754	Apr 19	Oct 17
Chicago Aurora Municipal Airport	5b	−15°F to −10°F	710	Apr 28	Oct 13
Chicago Midway Airport	6a	−10°F to −5°F	612	Apr 11	Oct 31
Chicago Ohare Intl Airport	6a	−10°F to −5°F	658	Apr 16	Oct 28
Chicago Palwaukee Airport	6a	−10°F to −5°F	636	Apr 19	Oct 26
Chicago Waukegan Regional Airport	6a	−10°F to −5°F	727	Apr 30	Oct 21
Decatur Airport	6a	−10°F to −5°F	675	Apr 16	Oct 22
Lawrenceville Intl Airport	6b	−5°F to 0°F	429	Apr 8	Oct 26
Mattoon Coles County Airport	6a	−10°F to −5°F	721	Apr 15	Oct 24
Moline Quad City Intl Airport	5b	−15°F to −10°F	592	Apr 24	Oct 18
Peoria Gtr Peoria Airport	6a	−10°F to −5°F	650	Apr 16	Oct 23
Quincy Regional Airport	6a	−10°F to −5°F	769	Apr 14	Oct 23
Rantoul	6a	−10°F to −5°F	740	Apr 21	Oct 18
Rockford Gtr Rockford Airport	5b	−15°F to −10°F	730	Apr 24	Oct 17
Shabbona 5 NNE	5b	−15°F to −10°F	861	Apr 28	Oct 10
Springfield Capital Airport	6a	−10°F to −5°F	594	Apr 14	Oct 20
West Chicago Dupage Airport	5b	−15°F to −10°F	754	Apr 25	Oct 19

Hardiness zones for 168 towns in Illinois

Each NOAA weather station is shown with the USDA zone of the nearest ZIP code (within 8 miles). Coldest night is the zone's range for the average annual extreme minimum temperature. Click a column to sort.

Filter by town


Albion	6b	−5°F to 0°F	530	Apr 4	Oct 28
Aledo	5b	−15°F to −10°F	730	Apr 22	Oct 19
Alton - Melvin Price L&d	7a	0°F to 5°F	405	Apr 4	Nov 5
Altona	5b	−15°F to −10°F	765	Apr 28	Oct 12
Anna 2 NNE	7a	0°F to 5°F	640	Apr 8	Oct 29
Antioch	5b	−15°F to −10°F	750	Apr 23	Oct 21
Athens 4SW	6a	−10°F to −5°F	594	Apr 19	Oct 19
Aurora	5b	−15°F to −10°F	660	Apr 19	Oct 23
Avon	5b	−15°F to −10°F	640	Apr 22	Oct 19
Barrington 3SW	5b	−15°F to −10°F	875	Apr 25	Oct 19
Belleville Siu Rsch	6b	−5°F to 0°F	450	Apr 12	Oct 20
Bentley	6a	−10°F to −5°F	650	Apr 13	Oct 22
Benton 2 N	7a	0°F to 5°F	445	Apr 4	Oct 28
Bloomington 5W	6a	−10°F to −5°F	852	Apr 21	Oct 20
Brownstown 4 SW	6b	−5°F to 0°F	530	Apr 3	Oct 24
Cahokia	7a	0°F to 5°F	400	Apr 6	Oct 27
Cahokia St Louis Airport	7a	0°F to 5°F	413	Apr 8	Oct 26
Cairo 3N	7a	0°F to 5°F	313	Apr 2	Oct 31
Carbondale Sewage Plt	7a	0°F to 5°F	390	Apr 9	Oct 22
Carbondale Southern Il Airport	7a	0°F to 5°F	406	Apr 9	Oct 22
Carlinville	6b	−5°F to 0°F	621	Apr 14	Oct 21
Carlyle Rsvr	6b	−5°F to 0°F	501	Apr 6	Oct 29
Carmi 3	7a	0°F to 5°F	335	Apr 15	Oct 19
Casey	6b	−5°F to 0°F	620	Apr 14	Oct 20
Champaign 3S	6a	−10°F to −5°F	721	Apr 15	Oct 24
Champaign 9 SW	6a	−10°F to −5°F	700	Apr 23	Oct 13
Champaign Willard Airport	6a	−10°F to −5°F	754	Apr 19	Oct 17
Channahon Dresden Island Dam	5b	−15°F to −10°F	505	Apr 16	Oct 26
Charleston	6a	−10°F to −5°F	700	Apr 15	Oct 23
Chenoa	5b	−15°F to −10°F	719	Apr 23	Oct 15
Chicago Aurora Municipal Airport	5b	−15°F to −10°F	710	Apr 28	Oct 13
Chicago Botanic Garden	6a	−10°F to −5°F	630	Apr 26	Oct 21
Chicago Midway Airport	6a	−10°F to −5°F	612	Apr 11	Oct 31
Chicago Midway Airport 3SW	6a	−10°F to −5°F	620	Apr 10	Nov 1
Chicago Northerly Island	6b	−5°F to 0°F	583	Apr 10	Nov 5
Chicago Ohare Intl Airport	6a	−10°F to −5°F	658	Apr 16	Oct 28
Chicago Palwaukee Airport	6a	−10°F to −5°F	636	Apr 19	Oct 26
Chicago Waukegan Regional Airport	6a	−10°F to −5°F	727	Apr 30	Oct 21
Compton 1 NW	5b	−15°F to −10°F	905	Apr 27	Oct 12
Congerville 2NW	5b	−15°F to −10°F	640	Apr 21	Oct 17
Crystal Lake 4NW	5b	−15°F to −10°F	940	Apr 25	Oct 22
Danville	6a	−10°F to −5°F	555	Apr 21	Oct 20
De Kalb	5b	−15°F to −10°F	873	Apr 24	Oct 18
Decatur Airport	6a	−10°F to −5°F	675	Apr 16	Oct 22
Decatur Wtp	6a	−10°F to −5°F	639	Apr 14	Oct 24
Dixon 1W	5b	−15°F to −10°F	660	Apr 21	Oct 19
Dixon Springs Agric Center	7a	0°F to 5°F	527	Apr 14	Oct 21
Du Quoin 4 SE	7a	0°F to 5°F	420	Apr 6	Oct 22
Dwight	5b	−15°F to −10°F	628	Apr 27	Oct 15
Effingham 3SW	6b	−5°F to 0°F	625	Apr 13	Oct 24
Elgin	5b	−15°F to −10°F	763	Apr 26	Oct 18
Elizabeth	5a	−20°F to −15°F	675	May 1	Oct 9
Fairfield Radio Wfiw	6b	−5°F to 0°F	430	Apr 7	Oct 26
Flora	6b	−5°F to 0°F	481	Apr 9	Oct 24
Flora 5 NW	6b	−5°F to 0°F	500	Apr 10	Oct 23
Freeport Waste Wtp	5a	−20°F to −15°F	750	Apr 26	Oct 13
Fulton L&d #13	5b	−15°F to −10°F	592	Apr 13	Oct 26
Galena	5a	−20°F to −15°F	822	Apr 26	Oct 15
Galesburg	5b	−15°F to −10°F	761	Apr 20	Oct 19
Galva	5b	−15°F to −10°F	810	Apr 26	Oct 12
Geneseo	5b	−15°F to −10°F	639	Apr 20	Oct 20
Gibson City	6a	−10°F to −5°F	750	Apr 21	Oct 17
Gladstone Dam 18	6a	−10°F to −5°F	538	Apr 8	Oct 29
Golden	6a	−10°F to −5°F	718	Apr 18	Oct 21
Grand Chain Dam 53	7a	0°F to 5°F	385	Apr 3	Nov 5
Grayville	7a	0°F to 5°F	435	Apr 7	Oct 25
Harrisburg	7a	0°F to 5°F	365	Apr 7	Oct 26
Havana	6a	−10°F to −5°F	463	Apr 17	Oct 19
Hennepin	5b	−15°F to −10°F	515	Apr 18	Oct 22
Hennepin Wtr Trmt Plt	5b	−15°F to −10°F	460	Apr 24	Oct 17
Hillsboro	6b	−5°F to 0°F	630	Apr 13	Oct 24
Hoopeston	6a	−10°F to −5°F	710	Apr 22	Oct 19
Illinois City Dam 16	5b	−15°F to −10°F	550	Apr 18	Oct 24
Iuka 12 SW	6b	−5°F to 0°F	590	Apr 9	Oct 24
Jacksonville 2	6a	−10°F to −5°F	626	Apr 17	Oct 21
Jacksonville 2E	6a	−10°F to −5°F	610	Apr 19	Oct 17
Jerseyville 2 SW	6b	−5°F to 0°F	630	Apr 14	Oct 19
Joliet Brandon Rd Dam	6a	−10°F to −5°F	543	Apr 19	Oct 25
Kankakee Metro Wastewater	5b	−15°F to −10°F	600	Apr 19	Oct 24
Kaskaskia River Navigation Lock	7a	0°F to 5°F	380	Apr 8	Oct 30
Kewanee 1 E	5b	−15°F to −10°F	780	Apr 24	Oct 17
Knoxville	5b	−15°F to −10°F	728	Apr 21	Oct 20
La Harpe	6a	−10°F to −5°F	690	Apr 21	Oct 19
Lacon	5b	−15°F to −10°F	458	Apr 20	Oct 17
Lake Villa 2NE	5b	−15°F to −10°F	840	Apr 24	Oct 23
Lawrenceville 2WSW	6b	−5°F to 0°F	451	Apr 12	Oct 25
Lawrenceville Intl Airport	6b	−5°F to 0°F	429	Apr 8	Oct 26
Lincoln	6a	−10°F to −5°F	583	Apr 20	Oct 16
Lisle-morton Arboretum	5b	−15°F to −10°F	680	Apr 28	Oct 16
Little Red School Hse	6a	−10°F to −5°F	715	Apr 19	Oct 22
Marengo	5b	−15°F to −10°F	815	Apr 28	Oct 12
Marseilles Lock	5b	−15°F to −10°F	490	Apr 27	Oct 17
Mason City 4SE	6a	−10°F to −5°F	600	Apr 17	Oct 18
Mattoon	6a	−10°F to −5°F	701	Apr 11	Oct 29
Mattoon Coles County Airport	6a	−10°F to −5°F	721	Apr 15	Oct 24
Mc Henry -wg Stratton L&d	5b	−15°F to −10°F	736	May 1	Oct 11
McLeansboro	6b	−5°F to 0°F	446	Apr 11	Oct 21
Minonk	5b	−15°F to −10°F	750	Apr 26	Oct 17
Moline Quad City Intl Airport	5b	−15°F to −10°F	592	Apr 24	Oct 18
Monmouth	5b	−15°F to −10°F	720	Apr 22	Oct 15
Monmouth 4NW	5b	−15°F to −10°F	724	Apr 22	Oct 14
Morris 1 NW	5b	−15°F to −10°F	524	Apr 20	Oct 23
Morrison	5b	−15°F to −10°F	632	Apr 26	Oct 13
Morrisonville	6a	−10°F to −5°F	630	Apr 12	Oct 20
Mount Carmel	6b	−5°F to 0°F	430	Apr 2	Oct 31
Mount Carroll	5a	−20°F to −15°F	640	May 2	Oct 7
Mount Vernon 3 NE	6b	−5°F to 0°F	490	Apr 11	Oct 22
Mundelein 4 WSW	5b	−15°F to −10°F	840	Apr 29	Oct 20
Nashville 1 E	6b	−5°F to 0°F	513	Apr 7	Oct 26
Neoga 4NW	6b	−5°F to 0°F	643	Apr 16	Oct 20
New Boston Dam 17	5b	−15°F to −10°F	548	Apr 14	Oct 24
Newton	6b	−5°F to 0°F	531	Apr 13	Oct 22
Newton 6 SSE	6b	−5°F to 0°F	510	Apr 13	Oct 22
Normal 4NE	6a	−10°F to −5°F	790	Apr 25	Oct 16
Ogden	6a	−10°F to −5°F	675	Apr 20	Oct 21
Olney 2S	6b	−5°F to 0°F	459	Apr 15	Oct 23
Ottawa 5SW	5b	−15°F to −10°F	525	Apr 20	Oct 22
Palestine	6b	−5°F to 0°F	450	Apr 12	Oct 22
Pana	6b	−5°F to 0°F	650	Apr 17	Oct 23
Paris Stp	6a	−10°F to −5°F	649	Apr 21	Oct 20
Park Forest	6a	−10°F to −5°F	710	Apr 23	Oct 20
Paw Paw 2S	5b	−15°F to −10°F	889	Apr 27	Oct 15
Paxton 2 WSW	6a	−10°F to −5°F	758	Apr 23	Oct 12
Peoria Gtr Peoria Airport	6a	−10°F to −5°F	650	Apr 16	Oct 23
Perry 6 NW	6a	−10°F to −5°F	650	Apr 18	Oct 15
Peru	5b	−15°F to −10°F	620	Apr 24	Oct 18
Petersburg 1E	6a	−10°F to −5°F	600	Apr 13	Oct 21
Piper City	6a	−10°F to −5°F	670	Apr 25	Oct 20
Pittsfield #2	6a	−10°F to −5°F	670	Apr 14	Oct 21
Polo 5NW	5b	−15°F to −10°F	856	Apr 29	Oct 7
Pontiac	6a	−10°F to −5°F	650	Apr 16	Oct 24
Prairie City 2S	6a	−10°F to −5°F	650	Apr 17	Oct 22
Princeton	5b	−15°F to −10°F	697	Apr 22	Oct 17
Princeville	5b	−15°F to −10°F	750	Apr 22	Oct 14
Quincy Dam 21	6a	−10°F to −5°F	483	Apr 8	Oct 30
Quincy Regional Airport	6a	−10°F to −5°F	769	Apr 14	Oct 23
Ramsey	6b	−5°F to 0°F	600	Apr 15	Oct 19
Rantoul	6a	−10°F to −5°F	740	Apr 21	Oct 18
Rend Lake Dam	7a	0°F to 5°F	455	Apr 4	Oct 27
Robinson	6b	−5°F to 0°F	535	Apr 13	Oct 22
Rochelle	5b	−15°F to −10°F	775	Apr 26	Oct 13
Rock Island L&d 15	5b	−15°F to −10°F	568	Apr 19	Oct 22
Rockford Gtr Rockford Airport	5b	−15°F to −10°F	730	Apr 24	Oct 17
Romeoville WFO	6a	−10°F to −5°F	660	Apr 20	Oct 22
Rosiclare 5NW	7a	0°F to 5°F	400	Apr 19	Oct 20
Rushville	6a	−10°F to −5°F	673	Apr 16	Oct 23
Salem	6b	−5°F to 0°F	550	Apr 9	Oct 26
Shabbona 5 NNE	5b	−15°F to −10°F	861	Apr 28	Oct 10
Shelbyville Dam	6a	−10°F to −5°F	650	Apr 10	Oct 24
Sidell 4N	6a	−10°F to −5°F	672	Apr 19	Oct 19
Smithland L&d	7a	0°F to 5°F	357	Apr 3	Oct 30
Sparta 1 W	7a	0°F to 5°F	535	Apr 12	Oct 22
Springfield #2	6a	−10°F to −5°F	599	Apr 15	Oct 22
Springfield Capital Airport	6a	−10°F to −5°F	594	Apr 14	Oct 20
Stockton 3 NNE	5a	−20°F to −15°F	970	Apr 27	Oct 9
Streamwood	5b	−15°F to −10°F	819	Apr 30	Oct 13
Streator 3 SE	5b	−15°F to −10°F	610	Apr 12	Oct 28
Sullivan 3S	6a	−10°F to −5°F	640	Apr 15	Oct 22
Tuscola	6a	−10°F to −5°F	651	Apr 15	Oct 20
Vandalia	6b	−5°F to 0°F	490	Apr 10	Oct 24
Virden	6b	−5°F to 0°F	675	Apr 7	Oct 29
Walnut	5b	−15°F to −10°F	671	Apr 24	Oct 14
Watseka 2 NW	5b	−15°F to −10°F	620	Apr 24	Oct 16
Waukegan	6a	−10°F to −5°F	700	Apr 30	Oct 19
West Chicago Dupage Airport	5b	−15°F to −10°F	754	Apr 25	Oct 19
White Hall 1 E	6a	−10°F to −5°F	580	Apr 13	Oct 22
Winchester	6a	−10°F to −5°F	551	Apr 18	Oct 20
Windsor	6a	−10°F to −5°F	690	Apr 16	Oct 22

Frequently asked questions

What hardiness zone is Illinois?

Illinois is in USDA hardiness zones 5a–7a on the 2023 USDA Plant Hardiness Zone Map. Zone 6a is the most common, covering 42% of Illinois's ZIP codes, and zone 5b covers 29%. Enter your ZIP code for your exact zone.

What does zone 6a mean?

Zone 6a means the average annual extreme minimum temperature, the coldest night of a typical winter, is −10°F to −5°F (−23°C to −21°C). Perennials, shrubs and trees rated for zone 6a or colder should survive winter there.

What is the coldest hardiness zone in Illinois?

Zone 5a is the coldest zone mapped in Illinois, found around Stockton 3 NNE, and zone 7a is the warmest, found around Cairo 3N.

Did Illinois's hardiness zones change in 2023?

The USDA released a new Plant Hardiness Zone Map in November 2023, based on 1991–2020 temperatures instead of 1976–2005. About half of the United States shifted half a zone warmer. Check your ZIP code here, because plant tags and older books may still list your 2012 zone.

When should I plant in zone 6a?

Hardiness zones don't set planting dates; frost dates do. Inside zone 6a in Illinois, the median last spring frost varies from April 8 to April 30. Look up your local frost dates and plant tender crops such as tomatoes after the 10%-risk last-frost date.

Zone and frost dates: use both

Your hardiness zone answers one question: will this plant survive the winter here? Choose perennials, shrubs, trees and bulbs rated for your zone or a colder one. For vegetables and annuals, what matters is the length of the frost-free season. See Illinois frost dates by town, or get a planting calendar for your ZIP code with start-indoors, transplant and sowing dates for 30 crops.

Sources and method

Zones are from the USDA 2023 Plant Hardiness Zone Map ZIP-code files published by the PRISM Climate Group, Oregon State University, based on 1991–2020 minimum temperatures. ZIP codes are assigned to states by USPS prefix. Town zones use the ZIP code nearest each NOAA 1991–2020 Climate Normals station. This is an independent tool, not an official USDA site. Full methodology.