S
M
T
W
T
F
S
30
68°
52°
31
68°
51°
1
67°
53°
2
69°
54°
3
67°
55°
4
67°
55°
5
64°
52°
6
65°
52°
7
67°
50°
8
64°
55°
9
64°
51°
10
66°
50°
11
63°
52°
12
64°
54°
13
62°
54°
14
63°
53°
15
66°
53°
16
66°
54°
17
Hist. Avg.
61°
51°
18
Hist. Avg.
60°
50°
19
Hist. Avg.
60°
50°
20
Hist. Avg.
60°
50°
21
Hist. Avg.
60°
50°
22
Hist. Avg.
60°
50°
23
Hist. Avg.
59°
50°
24
Hist. Avg.
59°
49°
25
Hist. Avg.
59°
49°
26
Hist. Avg.
59°
49°
27
Hist. Avg.
59°
49°
28
Hist. Avg.
59°
49°
29
Hist. Avg.
58°
49°
30
Hist. Avg.
58°
48°
1
Hist. Avg.
58°
48°
2
Hist. Avg.
58°
48°
3
Hist. Avg.
58°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Waterloo
Waterloo's September 2026 forecast shows daily high temperatures ranging from 62° to 69°, with overnight lows between 50° and 55°. The average high for September is 66° 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 Waterloo. See also: October | November | December.
