Counties in Illinois by average annual temperature

Massac County had the highest average annual temperature of 102 counties in 2014, at 55.6 °F. McHenry County had the lowest, at 44.3 °F. The median was 49.8 °F and the figure for Illinois was 49.5 °F. Source: NOAA National Centers for Environmental Information.

Highest55.6Massac County

Lowest44.3McHenry County

Median49.8102 counties

Illinois49.5History

Map of counties, 2014

Under 47
47 to 48
48 to 50
50 to 51
51 to 53
53 and over

°F, 2014. 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, 2014

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

Full ranking

Rank	Counties	2014 °F	Change on 2013
1	Massac County	55.6	-1.1%
2	Pulaski County	55.5	-1.4%
3	Alexander County	55.4	-1.4%
4	Pope County	54.8	-1.1%
5	Monroe County	54.7	-1.6%
6	Johnson County	54.6	-1.4%
7	Hardin County	54.5	-1.4%
8	Gallatin County	54.3	-1.8%
9	Union County	54.2	-2%
10	Saline County	54.1	-1.6%
10	St. Clair County	54.1	-1.8%
10	White County	54.1	-1.8%
13	Jackson County	53.8	-1.8%
13	Randolph County	53.8	-2%
13	Williamson County	53.8	-1.8%
16	Hamilton County	53.7	-1.6%
17	Franklin County	53.6	-2%
18	Perry County	53.4	-2%
19	Edwards County	53.3	-1.7%
20	Madison County	53.1	-2.2%
20	Wabash County	53.1	-2%
22	Wayne County	53	-1.9%
23	Jefferson County	52.8	-2.2%
23	Washington County	52.8	-2.4%
25	Clinton County	52.7	-2.4%
26	Lawrence County	52.2	-2.4%
27	Richland County	52.1	-2.4%
28	Bond County	52	-2.8%
28	Jersey County	52	-2.4%
30	Clay County	51.9	-2.4%
30	Marion County	51.9	-2.4%
32	Calhoun County	51.8	-2.6%
33	Crawford County	51.5	-2.6%
34	Fayette County	51.4	-2.8%
35	Jasper County	51.3	-2.7%
36	Greene County	51.1	-2.7%
36	Montgomery County	51.1	-2.9%
38	Effingham County	50.9	-3%
38	Macoupin County	50.9	-3%
38	Pike County	50.9	-2.1%
41	Clark County	50.7	-3.2%
42	Cumberland County	50.6	-3.3%
42	Scott County	50.6	-2.5%
44	Christian County	50.4	-3.1%
45	Sangamon County	50.2	-2.3%
46	Coles County	50.1	-3.5%
46	Morgan County	50.1	-2.7%
46	Shelby County	50.1	-3.3%
49	Adams County	50	-2.9%
50	Brown County	49.8	-2.4%
50	Douglas County	49.8	-3.5%
50	Menard County	49.8	-2.2%
53	Edgar County	49.7	-3.5%
53	Mason County	49.7	-2.4%
55	Cass County	49.6	-2.7%
55	Moultrie County	49.6	-3.5%
57	Logan County	49.5	-2.9%
58	Macon County	49.3	-3.7%
58	Piatt County	49.3	-3.5%
58	Tazewell County	49.3	-2.8%
61	Champaign County	49.1	-3.5%
62	Peoria County	49	-2.6%
63	De Witt County	48.9	-3.7%
63	Hancock County	48.9	-3.9%
63	Schuyler County	48.9	-3%
66	Vermilion County	48.8	-3.6%
67	Fulton County	48.7	-2.8%
68	McLean County	48.4	-4%
69	McDonough County	48.2	-3.4%
70	Woodford County	48.1	-4%
71	Ford County	48	-3.8%
72	Livingston County	47.8	-4%
73	Henderson County	47.7	-4.2%
74	Iroquois County	47.6	-4.6%
75	Marshall County	47.4	-4.6%
76	Grundy County	47.2	-4.3%
76	Knox County	47.2	-3.9%
78	Kankakee County	47.1	-4.7%
78	Warren County	47.1	-3.9%
80	Cook County	47	-3.5%
80	Mercer County	47	-3.5%
82	Rock Island County	46.9	-3.5%
82	Will County	46.9	-4.3%
84	LaSalle County	46.8	-4.3%
84	Putnam County	46.8	-5.3%
84	Stark County	46.8	-4.3%
87	Henry County	46.7	-3.9%
88	Kendall County	46.6	-4.1%
89	DuPage County	46.5	-3.3%
90	Whiteside County	46.3	-3.5%
91	Bureau County	45.9	-5.2%
92	Kane County	45.5	-3.6%
93	Lee County	45.4	-4.4%
94	DeKalb County	45.3	-3.8%
95	Carroll County	45.2	-4%
95	Lake County	45.2	-3.6%
95	Ogle County	45.2	-3.8%
98	Winnebago County	44.9	-3.4%
99	Stephenson County	44.7	-3.7%
100	Jo Daviess County	44.5	-3.9%
101	Boone County	44.4	-3.9%
102	McHenry County	44.3	-3.9%

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, 2014) [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, 2014. 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=2014. 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, 2014. 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=2014.

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, 2014 [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=2014 (Accessed: 12 October 2026).

BibTeX

@misc{noaa_counties_in_illinois_by_2014,
  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, 2014}},
  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=2014. 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, 2014
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=2014
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/average-annual-temperature/illinois-counties?period=2014.
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 55.6 °F in 2014, according to NOAA National Centers for Environmental Information.

Which county has the lowest average annual temperature?

McHenry County, with 44.3 °F in 2014.

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.