S
M
T
W
T
F
S
30
78°
56°
31
79°
53°
1
77°
54°
2
76°
53°
3
76°
53°
4
81°
58°
5
79°
56°
6
75°
57°
7
79°
56°
8
82°
59°
9
79°
61°
10
81°
60°
11
79°
58°
12
82°
51°
13
76°
49°
14
73°
49°
15
72°
50°
16
72°
49°
17
70°
50°
18
74°
54°
19
75°
52°
20
76°
48°
21
75°
47°
22
69°
44°
23
69°
45°
24
Hist. Avg.
74°
49°
25
Hist. Avg.
74°
49°
26
Hist. Avg.
73°
48°
27
Hist. Avg.
73°
48°
28
Hist. Avg.
72°
48°
29
Hist. Avg.
72°
47°
30
Hist. Avg.
71°
47°
1
Hist. Avg.
71°
46°
2
Hist. Avg.
70°
46°
3
Hist. Avg.
70°
45°
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 69° to 82°, with overnight lows between 44° and 61°. The average high for September is 76° 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.
