S
M
T
W
T
F
S
30
78°
56°
31
74°
65°
1
85°
68°
2
73°
68°
3
84°
67°
4
84°
68°
5
78°
60°
6
76°
56°
7
76°
53°
8
80°
51°
9
79°
57°
10
85°
64°
11
80°
51°
12
77°
65°
13
82°
62°
14
81°
53°
15
80°
63°
16
83°
59°
17
77°
58°
18
74°
52°
19
75°
53°
20
74°
55°
21
75°
50°
22
71°
52°
23
72°
49°
24
70°
53°
25
67°
44°
26
67°
46°
27
73°
53°
28
75°
50°
29
69°
44°
30
71°
52°
1
71°
48°
2
67°
45°
3
70°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Belvidere
Belvidere's September 2026 forecast shows daily high temperatures ranging from 67° to 85°, with overnight lows between 44° and 65°. The average high for September is 74° 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 Belvidere. See also: October | November | December.
