S
M
T
W
T
F
S
26
81°
62°
27
82°
61°
28
81°
60°
29
80°
60°
30
80°
55°
31
73°
54°
1
73°
54°
2
74°
55°
3
76°
56°
4
75°
55°
5
76°
54°
6
79°
60°
7
77°
60°
8
77°
59°
9
76°
60°
10
75°
53°
11
77°
53°
12
79°
54°
13
78°
59°
14
80°
60°
15
80°
57°
16
79°
61°
17
82°
60°
18
81°
56°
19
77°
52°
20
74°
51°
21
73°
51°
22
73°
52°
23
74°
51°
24
73°
51°
25
76°
52°
26
77°
51°
27
77°
51°
28
75°
53°
29
73°
52°
30
71°
51°
31
74°
55°
1
77°
48°
2
72°
49°
3
70°
48°
4
71°
49°
5
72°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Big Boulder
Big Boulder's August 2026 forecast shows daily high temperatures ranging from 70° to 82°, with overnight lows between 48° and 62°. The average high for August is 76° with an average low of 55°. 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 Big Boulder. See also: September | October | November.