S
M
T
W
T
F
S
30
78°
69°
31
91°
73°
1
95°
72°
2
96°
72°
3
94°
70°
4
96°
71°
5
91°
70°
6
84°
66°
7
82°
60°
8
87°
68°
9
81°
60°
10
79°
52°
11
80°
60°
12
82°
62°
13
78°
59°
14
75°
56°
15
75°
54°
16
76°
53°
17
76°
56°
18
74°
54°
19
73°
52°
20
74°
51°
21
74°
57°
22
73°
56°
23
75°
56°
24
77°
55°
25
78°
57°
26
77°
56°
27
77°
57°
28
78°
57°
29
77°
56°
30
75°
56°
1
72°
50°
2
63°
46°
3
63°
41°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Rock Falls
Rock Falls's September 2026 forecast shows daily high temperatures ranging from 63° to 87°, with overnight lows between 41° and 68°. The average high for September is 76° 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 Rock Falls. See also: October | November | December.
