S
M
T
W
T
F
S
30
81°
68°
31
87°
70°
1
93°
73°
2
94°
73°
3
91°
74°
4
91°
75°
5
82°
71°
6
80°
62°
7
81°
58°
8
85°
62°
9
80°
67°
10
77°
57°
11
81°
53°
12
86°
61°
13
73°
51°
14
70°
46°
15
83°
63°
16
75°
63°
17
81°
65°
18
71°
59°
19
70°
63°
20
68°
61°
21
66°
56°
22
65°
54°
23
66°
55°
24
67°
54°
25
71°
51°
26
74°
53°
27
72°
51°
28
70°
52°
29
70°
52°
30
71°
51°
1
70°
50°
2
69°
46°
3
64°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Naperville
Naperville's September 2026 forecast shows daily high temperatures ranging from 64° to 74°, with overnight lows between 46° and 61°. The average high for September is 69° with an average low of 53°. 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 Naperville. See also: October | November | December.
