S
M
T
W
T
F
S
30
83°
66°
31
83°
66°
1
84°
65°
2
79°
65°
3
81°
64°
4
81°
64°
5
83°
65°
6
83°
65°
7
84°
64°
8
85°
65°
9
81°
64°
10
78°
62°
11
82°
64°
12
83°
64°
13
83°
62°
14
72°
52°
15
71°
55°
16
72°
58°
17
73°
54°
18
81°
61°
19
82°
49°
20
81°
49°
21
70°
48°
22
69°
50°
23
67°
54°
24
71°
48°
25
71°
55°
26
76°
57°
27
76°
57°
28
78°
56°
29
78°
57°
30
77°
47°
1
76°
44°
2
67°
42°
3
62°
43°
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 62° to 85°, with overnight lows between 42° and 66°. The average high for September is 77° with an average low of 57°. 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.
