S
M
T
W
T
F
S
30
83°
70°
31
82°
66°
1
82°
64°
2
80°
65°
3
82°
65°
4
80°
65°
5
77°
70°
6
79°
70°
7
85°
71°
8
81°
70°
9
82°
71°
10
80°
70°
11
80°
66°
12
83°
69°
13
82°
68°
14
83°
70°
15
83°
69°
16
82°
69°
17
83°
68°
18
80°
65°
19
76°
64°
20
77°
65°
21
80°
65°
22
81°
66°
23
80°
66°
24
77°
63°
25
73°
60°
26
73°
60°
27
72°
59°
28
73°
59°
29
75°
61°
30
75°
63°
1
74°
61°
2
77°
62°
3
80°
66°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Fountain Valley
Fountain Valley's September 2026 forecast shows daily high temperatures ranging from 72° to 85°, with overnight lows between 59° and 71°. The average high for September is 79° with an average low of 66°. 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 Fountain Valley. See also: October | November | December.
