S
M
T
W
T
F
S
30
80°
64°
31
87°
69°
1
93°
73°
2
93°
71°
3
90°
71°
4
90°
72°
5
83°
68°
6
82°
60°
7
82°
57°
8
84°
60°
9
78°
69°
10
78°
57°
11
81°
54°
12
86°
58°
13
71°
52°
14
69°
44°
15
83°
63°
16
75°
61°
17
81°
64°
18
69°
60°
19
67°
62°
20
68°
59°
21
67°
56°
22
60°
52°
23
68°
53°
24
72°
50°
25
67°
49°
26
72°
47°
27
73°
46°
28
76°
45°
29
79°
48°
30
64°
59°
1
68°
49°
2
65°
42°
3
67°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in DeKalb
DeKalb's September 2026 forecast shows daily high temperatures ranging from 65° to 68°, with overnight lows between 42° and 49°. The average high for September is 67° with an average low of 46°. 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 DeKalb. See also: October | November | December.
