S
M
T
W
T
F
S
26
77°
60°
27
79°
60°
28
81°
61°
29
82°
62°
30
81°
63°
31
82°
62°
1
81°
61°
2
76°
56°
3
74°
54°
4
74°
54°
5
75°
60°
6
76°
60°
7
79°
59°
8
79°
61°
9
81°
61°
10
81°
60°
11
80°
60°
12
81°
61°
13
80°
61°
14
83°
59°
15
83°
60°
16
81°
60°
17
77°
61°
18
82°
61°
19
80°
60°
20
77°
53°
21
79°
51°
22
73°
51°
23
74°
52°
24
77°
54°
25
75°
50°
26
73°
51°
27
73°
51°
28
72°
50°
29
72°
49°
30
73°
48°
31
71°
48°
1
70°
47°
2
70°
50°
3
71°
50°
4
69°
52°
5
70°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in St. Johnsbury
St. Johnsbury's August 2026 forecast shows daily high temperatures ranging from 69° to 83°, with overnight lows between 47° and 63°. The average high for August is 77° with an average low of 56°. 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 St. Johnsbury. See also: September | October | November.