S
M
T
W
T
F
S
30
81°
67°
31
91°
70°
1
93°
74°
2
94°
74°
3
93°
75°
4
92°
74°
5
86°
72°
6
81°
64°
7
82°
63°
8
85°
62°
9
80°
67°
10
77°
61°
11
82°
58°
12
87°
64°
13
75°
54°
14
71°
52°
15
86°
65°
16
74°
65°
17
84°
67°
18
73°
63°
19
71°
63°
20
69°
60°
21
68°
58°
22
64°
55°
23
67°
58°
24
72°
59°
25
67°
50°
26
69°
54°
27
72°
53°
28
75°
53°
29
73°
59°
30
66°
57°
1
67°
53°
2
68°
55°
3
73°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Joliet
Joliet's September 2026 forecast shows daily high temperatures ranging from 66° to 75°, with overnight lows between 50° and 59°. The average high for September is 70° with an average low of 55°. 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 Joliet. See also: October | November | December.
