S
M
T
W
T
F
S
26
86°
69°
27
88°
68°
28
88°
68°
29
84°
66°
30
86°
67°
31
88°
69°
1
87°
68°
2
86°
69°
3
88°
70°
4
88°
70°
5
89°
69°
6
88°
69°
7
88°
68°
8
87°
69°
9
89°
68°
10
89°
68°
11
83°
67°
12
85°
67°
13
85°
65°
14
83°
66°
15
83°
68°
16
85°
68°
17
88°
67°
18
89°
69°
19
88°
68°
20
89°
69°
21
86°
68°
22
84°
69°
23
86°
69°
24
85°
68°
25
85°
65°
26
83°
63°
27
83°
63°
28
84°
69°
29
85°
69°
30
84°
68°
31
86°
67°
1
86°
66°
2
87°
65°
3
87°
64°
4
84°
62°
5
85°
61°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Fullerton
Fullerton's August 2026 forecast shows daily high temperatures ranging from 83° to 89°, with overnight lows between 61° and 70°. The average high for August is 86° with an average low of 67°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how August weather will actually feel in Fullerton. See also: September | October | November.
