S
M
T
W
T
F
S
30
83°
69°
31
87°
71°
1
94°
76°
2
94°
76°
3
89°
74°
4
91°
73°
5
87°
72°
6
81°
66°
7
77°
65°
8
76°
64°
9
77°
63°
10
77°
61°
11
77°
58°
12
75°
58°
13
75°
61°
14
76°
57°
15
78°
62°
16
79°
62°
17
78°
61°
18
78°
62°
19
79°
63°
20
79°
62°
21
78°
62°
22
79°
61°
23
78°
61°
24
78°
60°
25
77°
61°
26
77°
61°
27
78°
60°
28
77°
60°
29
76°
59°
30
75°
58°
1
75°
58°
2
74°
57°
3
75°
57°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in River Forest
River Forest's September 2026 forecast shows daily high temperatures ranging from 74° to 94°, with overnight lows between 57° and 76°. The average high for September is 79° with an average low of 63°. 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 River Forest. See also: October | November | December.
