S
M
T
W
T
F
S
26
89°
69°
27
89°
69°
28
88°
68°
29
88°
68°
30
87°
63°
31
81°
61°
1
81°
62°
2
82°
62°
3
83°
63°
4
83°
62°
5
84°
62°
6
86°
66°
7
85°
67°
8
84°
66°
9
83°
67°
10
84°
60°
11
84°
60°
12
84°
61°
13
85°
66°
14
87°
67°
15
88°
64°
16
87°
67°
17
89°
67°
18
88°
65°
19
85°
59°
20
81°
58°
21
81°
58°
22
82°
59°
23
81°
58°
24
81°
58°
25
83°
59°
26
85°
57°
27
85°
58°
28
82°
61°
29
82°
60°
30
79°
58°
31
82°
62°
1
85°
55°
2
82°
56°
3
78°
55°
4
79°
56°
5
79°
63°
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 78° to 89°, with overnight lows between 55° and 69°. The average high for August is 84° 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 August weather will actually feel in Fullerton. See also: September | October | November.
