S
M
T
W
T
F
S
30
75°
57°
31
76°
53°
1
75°
54°
2
74°
52°
3
73°
50°
4
73°
51°
5
74°
55°
6
74°
54°
7
73°
54°
8
74°
55°
9
73°
50°
10
74°
57°
11
77°
57°
12
77°
58°
13
79°
55°
14
77°
56°
15
77°
53°
16
76°
54°
17
70°
56°
18
78°
55°
19
76°
54°
20
75°
47°
21
78°
45°
22
71°
44°
23
70°
51°
24
72°
53°
25
Hist. Avg.
71°
48°
26
Hist. Avg.
71°
48°
27
Hist. Avg.
70°
48°
28
Hist. Avg.
70°
47°
29
Hist. Avg.
69°
47°
30
Hist. Avg.
69°
46°
1
Hist. Avg.
68°
46°
2
Hist. Avg.
68°
46°
3
Hist. Avg.
68°
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 70° to 79°, with overnight lows between 44° and 58°. The average high for September is 75° 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.
