Counties in Illinois by average annual temperature

Pulaski County had the highest average annual temperature of 102 counties in 2023, at 59.7 °F. Stephenson County had the lowest, at 50.1 °F. The median was 55 °F and the figure for Illinois was 54.7 °F. Source: NOAA National Centers for Environmental Information.

Highest59.7Pulaski County

Lowest50.1Stephenson County

Median55102 counties

Illinois54.7History

Top 40 counties, 2023

°F. Source: NOAA NCEI, NOAA Climate at a Glance, January to December average temperature, counties. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2023 °F	Change on 2022
1	Pulaski County	59.7	+3.5%
2	Alexander County	59.6	+3.3%
2	Massac County	59.6	+3.3%
4	Gallatin County	58.6	+3.5%
4	Hardin County	58.6	+3%
4	Pope County	58.6	+3.2%
7	Johnson County	58.5	+3.5%
7	Monroe County	58.5	+3.9%
9	Union County	58.4	+3.4%
9	White County	58.4	+3.7%
11	Saline County	58.2	+3.7%
12	Jackson County	58.1	+4.1%
12	Williamson County	58.1	+4.3%
14	Franklin County	58	+3.9%
14	Hamilton County	58	+3.6%
14	St. Clair County	58	+4.1%
17	Clinton County	57.9	+4.9%
17	Perry County	57.9	+3.9%
19	Washington County	57.8	+4.3%
20	Edwards County	57.7	+3.8%
20	Jefferson County	57.7	+3.8%
20	Randolph County	57.7	+3.6%
20	Wabash County	57.7	+4.2%
20	Wayne County	57.7	+3.6%
25	Madison County	57.6	+5.1%
26	Marion County	57.3	+4.8%
27	Bond County	57.1	+5.2%
27	Clay County	57.1	+4.4%
29	Jersey County	57	+4.6%
29	Lawrence County	57	+4.4%
29	Richland County	57	+4%
32	Calhoun County	56.7	+4.6%
32	Crawford County	56.7	+4.6%
32	Fayette County	56.7	+5.6%
35	Jasper County	56.6	+4.6%
36	Effingham County	56.4	+5.2%
36	Montgomery County	56.4	+6%
38	Macoupin County	56.3	+5.2%
39	Clark County	56.1	+4.7%
39	Greene County	56.1	+4.9%
41	Cumberland County	56	+4.9%
42	Christian County	55.9	+6.3%
43	Shelby County	55.6	+5.7%
44	Pike County	55.5	+5.3%
45	Coles County	55.4	+4.9%
46	Sangamon County	55.3	+5.7%
46	Scott County	55.3	+5.3%
48	Adams County	55.2	+5.7%
49	Douglas County	55.1	+5.2%
49	Moultrie County	55.1	+5.2%
51	Macon County	55	+5.4%
51	Mason County	55	+5.6%
51	Morgan County	55	+5.4%
54	Edgar County	54.9	+4.8%
55	Brown County	54.8	+6.2%
55	Logan County	54.8	+5.6%
55	Menard County	54.8	+5.6%
58	Cass County	54.7	+5.4%
58	Piatt County	54.7	+5.4%
58	Tazewell County	54.7	+5.6%
61	Schuyler County	54.6	+6.2%
62	Fulton County	54.5	+6%
62	Peoria County	54.5	+6.2%
64	De Witt County	54.4	+5.4%
65	Hancock County	54.3	+5.6%
66	Champaign County	54.2	+5.4%
67	McLean County	54	+5.5%
68	McDonough County	53.8	+6.1%
68	Woodford County	53.8	+5.5%
70	Livingston County	53.6	+5.7%
71	Henderson County	53.5	+6.2%
71	Vermilion County	53.5	+4.5%
73	Ford County	53.4	+5.7%
73	Marshall County	53.4	+6%
75	Mercer County	53.1	+6.4%
75	Rock Island County	53.1	+6.4%
77	Iroquois County	53	+5.2%
77	Putnam County	53	+6%
77	Warren County	53	+6.6%
80	Knox County	52.9	+6.4%
81	Stark County	52.8	+6.5%
82	Cook County	52.7	+4.8%
82	Grundy County	52.7	+5.4%
82	Kankakee County	52.7	+5.2%
85	Henry County	52.5	+6.5%
86	Bureau County	52.3	+6.3%
86	Will County	52.3	+5%
88	LaSalle County	52.2	+5.7%
88	Whiteside County	52.2	+6.3%
90	DuPage County	52.1	+5%
91	Kendall County	51.9	+5.5%
92	Lee County	51.6	+6.4%
93	Lake County	51.5	+5.3%
94	Kane County	51.2	+5.6%
95	DeKalb County	51	+6.3%
96	Carroll County	50.9	+6%
96	Ogle County	50.9	+5.4%
98	Winnebago County	50.7	+5.2%
99	Boone County	50.5	+5%
100	McHenry County	50.2	+4.4%
101	Jo Daviess County	50.1	+6.4%
101	Stephenson County	50.1	+5.7%

Other periods

About this ranking

Mean air temperature from January to December, in degrees Fahrenheit: the average of the 12 monthly mean temperatures. NOAA computes it from its climate divisional dataset (nClimDiv): station readings interpolated onto a 5 km grid and averaged over the area.

Values are area averages, so a county with mountains and valleys has one value for very different local climates. NOAA revises the last two years every month.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.

How to cite

NOAA National Centers for Environmental Information, Climate at a Glance. NOAA Climate at a Glance, January to December average temperature, counties. From the NOAA Monthly U.S. Climate Divisional Database (nClimDiv), doi:10.7289/V5M32STR. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

NOAA National Centers for Environmental Information. (2026). NOAA Climate at a Glance, January to December average temperature, counties (Counties in Illinois by average annual temperature, 2023) [Data set]. Retrieved October 12, 2026, from https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping

MLA 9

NOAA Climate at a Glance, January to December average temperature, counties, Counties in Illinois by average annual temperature, 2023. NOAA National Centers for Environmental Information, 6 Oct. 2026, https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping. Invokely, https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2023. Accessed 12 Oct. 2026.

Chicago (author-date)

NOAA National Centers for Environmental Information. 2026. NOAA Climate at a Glance, January to December average temperature, counties. Counties in Illinois by average annual temperature, 2023. Dataset. Accessed October 12, 2026. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping. Also distributed by Invokely, https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2023.

Harvard

NOAA National Centers for Environmental Information (2026) NOAA Climate at a Glance, January to December average temperature, counties, Counties in Illinois by average annual temperature, 2023 [Dataset]. Available at: https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping, via Invokely: https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2023 (Accessed: 12 October 2026).

BibTeX

@misc{noaa_counties_in_illinois_by_2023,
  author = {{NOAA National Centers for Environmental Information}},
  title = {{NOAA Climate at a Glance, January to December average temperature, counties: Counties in Illinois by average annual temperature, 2023}},
  year = {2026},
  howpublished = {Data set},
  url = {https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2023. Publisher attribution: NOAA National Centers for Environmental Information, Climate at a Glance. NOAA Climate at a Glance, January to December average temperature, counties. From the NOAA Monthly U.S. Climate Divisional Database (nClimDiv), doi:10.7289/V5M32STR. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping. Retrieved 2026-10-12.},
}

RIS

TY  - DATA
AU  - NOAA National Centers for Environmental Information
TI  - NOAA Climate at a Glance, January to December average temperature, counties: Counties in Illinois by average annual temperature, 2023
PY  - 2026
DA  - 2026/10/06
PB  - NOAA National Centers for Environmental Information
DB  - Invokely
UR  - https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping
L2  - https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2023
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2023.
N1  - Publisher attribution: NOAA National Centers for Environmental Information, Climate at a Glance. NOAA Climate at a Glance, January to December average temperature, counties. From the NOAA Monthly U.S. Climate Divisional Database (nClimDiv), doi:10.7289/V5M32STR. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/mapping. Retrieved 2026-10-12.
ER  -

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Questions

Which county has the highest average annual temperature?

Pulaski County, with 59.7 °F in 2023, according to NOAA National Centers for Environmental Information.

Which county has the lowest average annual temperature?

Stephenson County, with 50.1 °F in 2023.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: NOAA National Centers for Environmental Information, NOAA Climate at a Glance, January to December average temperature, counties. Retrieved 2026-10-12.