S
M
T
W
T
F
S
30
76°
58°
31
78°
61°
1
76°
60°
2
82°
52°
3
75°
51°
4
72°
52°
5
72°
51°
6
73°
56°
7
80°
59°
8
82°
60°
9
81°
55°
10
76°
52°
11
74°
59°
12
75°
55°
13
79°
50°
14
72°
50°
15
70°
47°
16
71°
50°
17
74°
56°
18
78°
46°
19
71°
53°
20
72°
47°
21
73°
53°
22
70°
55°
23
78°
56°
24
77°
55°
25
77°
55°
26
76°
54°
27
77°
54°
28
77°
52°
29
75°
53°
30
75°
54°
1
77°
49°
2
76°
44°
3
74°
42°
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 70° to 82°, with overnight lows between 42° and 61°. The average high for September is 75° 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 Rock Falls. See also: October | November | December.
