S
M
T
W
T
F
S
26
97°
69°
27
97°
68°
28
96°
68°
29
97°
69°
30
97°
69°
31
96°
68°
1
96°
68°
2
97°
69°
3
97°
68°
4
96°
67°
5
96°
68°
6
95°
68°
7
96°
69°
8
96°
69°
9
95°
68°
10
97°
68°
11
96°
65°
12
90°
62°
13
90°
62°
14
91°
63°
15
94°
67°
16
95°
68°
17
94°
63°
18
92°
62°
19
93°
66°
20
92°
68°
21
96°
67°
22
95°
66°
23
95°
65°
24
96°
63°
25
93°
63°
26
93°
62°
27
92°
62°
28
92°
63°
29
93°
62°
30
92°
62°
31
92°
63°
1
93°
61°
2
91°
62°
3
90°
62°
4
90°
63°
5
91°
63°
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 97°, with overnight lows between 61° and 69°. The average high for August is 94° with an average low of 65°. 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.
