Illinois September 1999 Average Temperature Rankings
1901-2000
Degrees Fahrenheit
1
65.2
66.2
-1.0
41
89
1918
1925,1933
1996
1998
bottom-third
1968
2
68.5
69.8
-1.3
31
99
1967
1936
1994
1998
bottom-third
3
71.8
71.7
0.1
68
62
1967
1936
1997
1998
normal
1932,1952,2006,2017
4
71.9
71.7
0.2
70
60
1915,1924
1936
1997
1998
normal
1977
5
70.4
69.7
0.7
83
47
1924
1936
1997
1998
normal
1932,1970
6
67.7
66.7
1.0
90
40
1907
2010
1997
1998
top-third
1952,1953,2006,2011,2023
7
63.5
62.9
0.6
85
45
1924
2012
1997
1998
normal
1895,1896,1908,1913,1963,1995,2001,2004
8
60.2
58.7
1.5
111
19
1904
2012
1997
1998
top-third
1922,1931,1953,1986,2002,2007,2018
9
56.3
54.9
1.4
98
32
1904,1912
2012
1997
1998
top-third
1930,1944,1983
10
54.2
52.4
1.8
105
24
1904
2012
1997
1998
top-third
1955
11
53.4
51.4
2.0
114
15
1904
2012
1997
1998
top-third
2006
12
53.7
51.6
2.1
116
13
1904
2012
1997
1998
top-tenth
2023
18
58.7
56.7
2.0
123
6
1904,1918
2012
1998
1932
top-tenth
2006
24
54.0
51.6
2.4
124
4
1979
2017
1998
1999
top-tenth
2018
36
52.8
51.6
1.2
105
22
1979
2018
1998
1992
top-third
1921,1992
48
52.1
51.6
0.5
81
45
1905
2019
1998
1993
normal
1987
60
52.3
51.6
0.7
87
38
1906
2020
1998
1992
top-third
1958,1989,2011