S
M
T
W
T
F
S
26
76°
55°
27
76°
54°
28
82°
51°
29
88°
54°
30
76°
61°
31
86°
63°
1
80°
56°
2
76°
49°
3
80°
49°
4
75°
49°
5
74°
53°
6
78°
60°
7
74°
53°
8
74°
54°
9
77°
54°
10
75°
54°
11
74°
52°
12
73°
55°
13
73°
54°
14
74°
55°
15
73°
54°
16
73°
55°
17
72°
50°
18
68°
54°
19
74°
55°
20
68°
55°
21
71°
56°
22
75°
56°
23
75°
55°
24
69°
54°
25
68°
54°
26
67°
53°
27
67°
54°
28
72°
55°
29
73°
54°
30
74°
55°
31
74°
53°
1
69°
52°
2
66°
53°
3
69°
54°
4
73°
55°
5
72°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Thunder Bay
Thunder Bay's August 2026 forecast shows daily high temperatures ranging from 66° to 78°, with overnight lows between 49° and 60°. The average high for August is 72° with an average low of 54°. 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 Thunder Bay. See also: September | October | November.
