S
M
T
W
T
F
S
30
100°
69°
31
100°
74°
1
99°
73°
2
98°
73°
3
95°
74°
4
97°
73°
5
100°
75°
6
103°
75°
7
102°
73°
8
101°
73°
9
98°
73°
10
97°
73°
11
96°
72°
12
97°
71°
13
99°
72°
14
95°
69°
15
91°
68°
16
91°
69°
17
90°
68°
18
93°
65°
19
90°
67°
20
87°
61°
21
91°
68°
22
90°
68°
23
91°
67°
24
90°
67°
25
89°
66°
26
88°
65°
27
89°
65°
28
89°
66°
29
87°
65°
30
84°
62°
1
78°
55°
2
76°
53°
3
76°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in De Kalb
De Kalb's September 2026 forecast shows daily high temperatures ranging from 76° to 102°, with overnight lows between 52° and 73°. The average high for September is 91° with an average low of 66°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in De Kalb. See also: October | November | December.
