S
M
T
W
T
F
S
30
91°
60°
31
85°
60°
1
85°
64°
2
89°
65°
3
89°
64°
4
88°
63°
5
89°
64°
6
88°
65°
7
88°
63°
8
87°
62°
9
86°
60°
10
85°
58°
11
84°
60°
12
88°
62°
13
87°
62°
14
87°
61°
15
Hist. Avg.
85°
61°
16
Hist. Avg.
85°
60°
17
Hist. Avg.
84°
60°
18
Hist. Avg.
84°
59°
19
Hist. Avg.
84°
59°
20
Hist. Avg.
83°
58°
21
Hist. Avg.
83°
58°
22
Hist. Avg.
83°
58°
23
Hist. Avg.
82°
57°
24
Hist. Avg.
82°
57°
25
Hist. Avg.
82°
56°
26
Hist. Avg.
81°
56°
27
Hist. Avg.
81°
55°
28
Hist. Avg.
80°
55°
29
Hist. Avg.
80°
54°
30
Hist. Avg.
80°
54°
1
Hist. Avg.
80°
54°
2
Hist. Avg.
79°
53°
3
Hist. Avg.
79°
53°
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 84° to 91°, with overnight lows between 58° and 65°. The average high for September is 87° with an average low of 62°. 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.
