How Does the Number of 100-Degree Days Compare to Records?

Temperatures across central and southeast Illinois have reached 100 degrees an unusually high number of times so far this year. A review of climate records indicates that 1988 was the most recent year that had a comparable number of 100-degree days.  However, there is still a ways to go before any records are broken for the most 100-degree days in a calendar year.

Here are some statistics for area cities through July 31.

Location Number of 
100-degree 
days in 2012
Hottest temperature
this year
Last time it
was warmer
Top 5 years with
highs >=100 degrees
Charleston 14 days 105° on June 29 and July 6 July 19, 1954 (107°) 1936 (26 days)
1914 (25 days)
1933 (23 days)
1934 (21 days)
1930 (20 days)
Decatur 5 days 102° on July 6 Aug. 18, 1988 (104°) 1936 (26 days)
1934 (23 days)
1913 and 1931 (17 days)
1930 (16 days)
1916 (14 days)
Jacksonville 10 days 105° on July 8 July 20, 1954 (107°) 1936 (36 days)
1934 (29 days)
1954 (18 days)
1930 (16 days)
1913 and 1931 (15 days)
Lincoln 6 days 102° on July 6 and 7 Aug. 21, 1983 (104°)

1936 (26 days)
1934 (19 days)
1916 (16 days)
1913 and 1930 (12 days)
1931 and 1954 (11 days)

Normal 12 days 

(tied for 5th most 
in a calendar year)
107° on July 8 July 15, 1936 (114°) 1936 (22 days)
1916 (20 days)
1934 (17 days)
1931 (15 days)
1894 (12 days)
Olney 15 days

(tied for 4th most 
in a calendar year)
105° on June 29 and July 6 Sep. 2, 1953 (106°) 1936 (39 days)
1914 and 1930 (24 days)
1954 (19 days)
1901 (15 days)
1931 (14 days)
Palestine 15 days

(tied for 5th most
in a calendar year)
105° on July 7 Aug. 18, 1988 (107°) 1954 (30 days)
1936 (27 days)
1930 and 1988 (26 days)
1953 (23 days)
1913, 1933, 1934 (15 days)
Paris 11 days 105° on June 29 July 18, 1954 (107°) 1936 (31 days)
1913 (21 days)
1934 (14 days)
1930 (13 days)
1896 and 1988 (12 days)
Peoria 8 days 104° on July 7 and 23 June 25, 1988 (105°) 1936 (23 days)
1934 (18 days)
1887 (11 days)
1983 (10 days)
1912, 1930, 1931, 1988 (9 days)
Springfield 11 days

(3rd most in
a calendar year)
104° on July 6 and 7 July 13, 1966 (106°) 1936 (29 days)
1934 (18 days)
1931 (10 days)
1954 (9 days)
1966 (8 days)
Urbana 9 days

(3rd most in 
a calendar year)
103° on July 6 and 7 July 14, 1954 (109°) 1936 (15 days)
1934 (11 days)
1954 (8 days)
1930 (7 days)
1988 (5 days)


Normal annual number of days with highs at least 100 degrees.  Image courtesy of the Illinois State Water Survey. 

Normal number of days per year with highs of at least 100 degrees.  Image courtesy of the Illinois State Water Survey.

Springfield has 25 days with high temperatures at or above 90 degrees in July 2012. This is tied for 3rd most days with 27 days in 1901, 26 days in 1916 and 25 days in 1921, 1936 and 2012.

Peoria has 24 days with high temperatures at or above 90 degrees in July 2012.  This is tied for 2nd most days that warm in July with 26 days in 1887 & 1901 and 24 days in 1916 and 2012.  



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