S
M
T
W
T
F
S
30
89°
73°
31
93°
72°
1
94°
73°
2
97°
76°
3
88°
71°
4
88°
70°
5
82°
62°
6
79°
56°
7
79°
55°
8
81°
55°
9
81°
68°
10
77°
54°
11
77°
60°
12
78°
55°
13
72°
53°
14
71°
67°
15
74°
59°
16
68°
59°
17
72°
54°
18
70°
53°
19
68°
50°
20
72°
52°
21
70°
51°
22
73°
53°
23
72°
48°
24
76°
55°
25
72°
54°
26
76°
55°
27
75°
54°
28
75°
54°
29
72°
53°
30
73°
50°
1
69°
49°
2
66°
51°
3
70°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Fontana-on-Geneva Lake
Fontana-on-Geneva Lake's September 2026 forecast shows daily high temperatures ranging from 66° to 78°, with overnight lows between 48° and 67°. The average high for September is 72° with an average low of 54°. 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 Fontana-on-Geneva Lake. See also: October | November | December.
