S
M
T
W
T
F
S
26
75°
59°
27
78°
62°
28
74°
65°
29
69°
61°
30
75°
56°
31
78°
56°
1
78°
61°
2
76°
66°
3
73°
62°
4
78°
57°
5
80°
66°
6
81°
66°
7
80°
66°
8
78°
64°
9
79°
66°
10
78°
66°
11
71°
63°
12
80°
66°
13
81°
64°
14
83°
62°
15
84°
67°
16
84°
66°
17
79°
57°
18
78°
59°
19
79°
60°
20
79°
63°
21
80°
63°
22
82°
61°
23
78°
58°
24
75°
57°
25
76°
56°
26
80°
55°
27
82°
60°
28
74°
52°
29
75°
53°
30
79°
58°
31
80°
59°
1
82°
59°
2
81°
58°
3
82°
59°
4
81°
59°
5
80°
57°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Johnstown
Johnstown's August 2026 forecast shows daily high temperatures ranging from 74° to 84°, with overnight lows between 52° and 67°. The average high for August is 80° with an average low of 60°. 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 Johnstown. See also: September | October | November.