S
M
T
W
T
F
S
30
84°
68°
31
87°
69°
1
88°
73°
2
89°
72°
3
79°
69°
4
88°
68°
5
77°
64°
6
75°
59°
7
78°
59°
8
77°
59°
9
82°
67°
10
78°
59°
11
79°
58°
12
82°
63°
13
67°
48°
14
70°
45°
15
73°
62°
16
70°
58°
17
66°
60°
18
67°
60°
19
66°
61°
20
63°
58°
21
62°
54°
22
61°
46°
23
64°
52°
24
66°
54°
25
69°
47°
26
68°
47°
27
68°
47°
28
71°
52°
29
70°
55°
30
63°
54°
1
69°
51°
2
67°
50°
3
70°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Waukesha
Waukesha's September 2026 forecast shows daily high temperatures ranging from 63° to 71°, with overnight lows between 47° and 55°. The average high for September is 68° with an average low of 51°. 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 Waukesha. See also: October | November | December.
