S
M
T
W
T
F
S
26
99°
71°
27
99°
70°
28
96°
68°
29
95°
67°
30
97°
66°
31
102°
67°
1
102°
70°
2
101°
69°
3
98°
67°
4
95°
67°
5
94°
66°
6
97°
68°
7
98°
70°
8
102°
71°
9
99°
72°
10
96°
73°
11
97°
72°
12
92°
69°
13
87°
68°
14
88°
66°
15
91°
65°
16
95°
65°
17
98°
67°
18
99°
70°
19
103°
71°
20
99°
69°
21
101°
69°
22
102°
69°
23
102°
69°
24
103°
72°
25
103°
72°
26
104°
72°
27
103°
71°
28
100°
69°
29
101°
69°
30
99°
68°
31
94°
66°
1
92°
64°
2
94°
65°
3
90°
69°
4
92°
65°
5
95°
68°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Rancho Cucamonga
Rancho Cucamonga's August 2026 forecast shows daily high temperatures ranging from 90° to 104°, with overnight lows between 64° and 72°. The average high for August is 98° with an average low of 69°. 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 Rancho Cucamonga. See also: September | October | November.
