Counties in Illinois by average annual temperature

Massac County had the highest average annual temperature of 102 counties in 2024, at 60.4 °F. Stephenson County had the lowest, at 51.2 °F. The median was 55.6 °F and the figure for Illinois was 55.5 °F. Source: NOAA National Centers for Environmental Information.

Highest60.4Massac County

Lowest51.2Stephenson County

Median55.6102 counties

Illinois55.5History

Map of counties, 2024

Under 54
54 to 56
56 to 57
57 to 58
58 and over

°F, 2024. Source: NOAA NCEI, NOAA Climate at a Glance, January to December average temperature, counties. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2024

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

Full ranking

Rank	Counties	2024 °F	Change on 2023
1	Massac County	60.4	+1.3%
1	Pulaski County	60.4	+1.2%
3	Alexander County	60.3	+1.2%
4	Pope County	59.3	+1.2%
5	Gallatin County	59.2	+1%
5	Hardin County	59.2	+1%
5	White County	59.2	+1.4%
8	Johnson County	59.1	+1%
9	Franklin County	59	+1.7%
9	Jackson County	59	+1.5%
9	Perry County	59	+1.9%
9	Union County	59	+1%
13	Monroe County	58.9	+0.7%
14	Hamilton County	58.7	+1.2%
14	Saline County	58.7	+0.9%
14	Williamson County	58.7	+1%
17	Edwards County	58.4	+1.2%
17	Jefferson County	58.4	+1.2%
17	Randolph County	58.4	+1.2%
17	Wabash County	58.4	+1.2%
21	St. Clair County	58.3	+0.5%
21	Washington County	58.3	+0.9%
23	Clinton County	58.1	+0.3%
23	Wayne County	58.1	+0.7%
25	Madison County	58	+0.7%
26	Marion County	57.8	+0.9%
27	Bond County	57.6	+0.9%
27	Clay County	57.6	+0.9%
27	Lawrence County	57.6	+1.1%
27	Richland County	57.6	+1.1%
31	Jersey County	57.5	+0.9%
32	Crawford County	57.3	+1.1%
32	Jasper County	57.3	+1.2%
34	Calhoun County	57.1	+0.7%
34	Fayette County	57.1	+0.7%
36	Clark County	56.8	+1.2%
36	Effingham County	56.8	+0.7%
38	Macoupin County	56.7	+0.7%
38	Montgomery County	56.7	+0.5%
40	Cumberland County	56.6	+1.1%
40	Greene County	56.6	+0.9%
42	Christian County	56.1	+0.4%
42	Pike County	56.1	+1.1%
44	Scott County	56	+1.3%
45	Adams County	55.9	+1.3%
45	Coles County	55.9	+0.9%
45	Shelby County	55.9	+0.5%
48	Morgan County	55.7	+1.3%
48	Sangamon County	55.7	+0.7%
50	Douglas County	55.6	+0.9%
50	Edgar County	55.6	+1.3%
50	Mason County	55.6	+1.1%
53	Brown County	55.5	+1.3%
53	Cass County	55.5	+1.5%
55	Moultrie County	55.4	+0.5%
56	Fulton County	55.3	+1.5%
56	Schuyler County	55.3	+1.3%
58	Menard County	55.2	+0.7%
58	Peoria County	55.2	+1.3%
58	Tazewell County	55.2	+0.9%
61	Macon County	55.1	+0.2%
61	Piatt County	55.1	+0.7%
63	Logan County	55	+0.4%
64	Champaign County	54.9	+1.3%
64	Hancock County	54.9	+1.1%
66	De Witt County	54.7	+0.6%
67	McDonough County	54.5	+1.3%
67	Vermilion County	54.5	+1.9%
69	McLean County	54.4	+0.7%
69	Woodford County	54.4	+1.1%
71	Marshall County	54.3	+1.7%
72	Ford County	54.2	+1.5%
72	Livingston County	54.2	+1.1%
74	Henderson County	54.1	+1.1%
75	Cook County	54	+2.5%
75	Grundy County	54	+2.5%
75	Stark County	54	+2.3%
78	Iroquois County	53.9	+1.7%
78	Knox County	53.9	+1.9%
78	Putnam County	53.9	+1.7%
81	Mercer County	53.8	+1.3%
81	Warren County	53.8	+1.5%
83	Kankakee County	53.7	+1.9%
83	Rock Island County	53.7	+1.1%
85	Will County	53.6	+2.5%
86	DuPage County	53.5	+2.7%
86	Henry County	53.5	+1.9%
88	Kendall County	53.4	+2.9%
89	Bureau County	53.3	+1.9%
89	LaSalle County	53.3	+2.1%
91	Whiteside County	53.2	+1.9%
92	Lake County	52.7	+2.3%
92	Lee County	52.7	+2.1%
94	Kane County	52.6	+2.7%
95	DeKalb County	52.3	+2.5%
96	Ogle County	52.2	+2.6%
96	Winnebago County	52.2	+3%
98	Carroll County	52.1	+2.4%
99	Boone County	52	+3%
100	McHenry County	51.7	+3%
101	Jo Daviess County	51.2	+2.2%
101	Stephenson County	51.2	+2.2%

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, 2024) [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, 2024. 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=2024. 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, 2024. 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=2024.

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, 2024 [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=2024 (Accessed: 12 October 2026).

BibTeX

@misc{noaa_counties_in_illinois_by_2024,
  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, 2024}},
  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=2024. 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, 2024
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=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2024.
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?

Massac County, with 60.4 °F in 2024, according to NOAA National Centers for Environmental Information.

Which county has the lowest average annual temperature?

Stephenson County, with 51.2 °F in 2024.

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.