S
M
T
W
T
F
S
30
85°
65°
31
85°
64°
1
86°
64°
2
86°
65°
3
87°
65°
4
88°
66°
5
88°
68°
6
84°
66°
7
84°
64°
8
88°
65°
9
86°
66°
10
87°
65°
11
87°
65°
12
86°
64°
13
86°
64°
14
85°
63°
15
86°
64°
16
Hist. Avg.
85°
63°
17
Hist. Avg.
85°
62°
18
Hist. Avg.
84°
62°
19
Hist. Avg.
84°
62°
20
Hist. Avg.
84°
62°
21
Hist. Avg.
84°
61°
22
Hist. Avg.
83°
61°
23
Hist. Avg.
83°
60°
24
Hist. Avg.
83°
60°
25
Hist. Avg.
82°
60°
26
Hist. Avg.
82°
59°
27
Hist. Avg.
82°
59°
28
Hist. Avg.
81°
59°
29
Hist. Avg.
81°
58°
30
Hist. Avg.
81°
58°
1
Hist. Avg.
80°
58°
2
Hist. Avg.
80°
57°
3
Hist. Avg.
80°
57°
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 88°, with overnight lows between 63° and 68°. The average high for September is 86° with an average low of 65°. 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.
