S
M
T
W
T
F
S
30
80°
55°
31
81°
58°
1
81°
60°
2
80°
59°
3
80°
60°
4
79°
59°
5
79°
58°
6
77°
58°
7
77°
57°
8
76°
57°
9
78°
56°
10
78°
56°
11
77°
55°
12
79°
56°
13
79°
58°
14
78°
57°
15
77°
57°
16
77°
56°
17
75°
57°
18
72°
53°
19
72°
45°
20
68°
53°
21
69°
53°
22
70°
46°
23
67°
45°
24
67°
47°
25
69°
52°
26
72°
53°
27
66°
46°
28
65°
45°
29
65°
45°
30
66°
51°
1
65°
52°
2
64°
43°
3
64°
41°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Joliett
Joliett's September 2026 forecast shows daily high temperatures ranging from 64° to 81°, with overnight lows between 41° and 60°. The average high for September is 73° 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 Joliett. See also: October | November | December.
