S
M
T
W
T
F
S
30
92°
73°
31
87°
68°
1
92°
60°
2
90°
61°
3
88°
62°
4
86°
63°
5
88°
69°
6
88°
71°
7
93°
69°
8
91°
68°
9
90°
65°
10
90°
65°
11
96°
67°
12
94°
64°
13
95°
66°
14
93°
61°
15
95°
66°
16
95°
65°
17
94°
64°
18
91°
59°
19
88°
59°
20
88°
60°
21
91°
62°
22
92°
62°
23
91°
61°
24
88°
57°
25
82°
55°
26
82°
55°
27
81°
54°
28
82°
55°
29
83°
56°
30
83°
56°
1
82°
55°
2
84°
60°
3
88°
62°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Fontana
Fontana's September 2026 forecast shows daily high temperatures ranging from 81° to 96°, with overnight lows between 54° and 71°. The average high for September is 89° with an average low of 62°. 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. See also: October | November | December.
