S
M
T
W
T
F
S
30
79°
70°
31
86°
72°
1
86°
70°
2
82°
66°
3
84°
68°
4
88°
68°
5
81°
66°
6
77°
66°
7
77°
63°
8
77°
63°
9
82°
63°
10
77°
55°
11
79°
57°
12
75°
57°
13
70°
48°
14
64°
48°
15
72°
64°
16
71°
53°
17
75°
63°
18
66°
59°
19
66°
59°
20
68°
55°
21
57°
52°
22
63°
50°
23
66°
46°
24
66°
48°
25
70°
57°
26
64°
52°
27
61°
57°
28
72°
59°
29
72°
54°
30
70°
64°
1
68°
48°
2
64°
41°
3
70°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Decorah
Decorah's September 2026 forecast shows daily high temperatures ranging from ° to °, with overnight lows between ° and °. The average high for September is ° with an average low of °. 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 Decorah. See also: October | November | December.
