S
M
T
W
T
F
S
29
35°
9°
30
37°
17°
31
32°
14°
1
26°
1°
2
32°
23°
3
40°
25°
4
33°
26°
5
43°
23°
6
32°
7°
7
36°
0°
8
34°
23°
9
37°
31°
10
44°
31°
11
47°
23°
12
43°
33°
13
53°
33°
14
44°
31°
15
51°
35°
16
54°
33°
17
53°
35°
18
32°
18°
19
35°
17°
20
42°
31°
21
54°
29°
22
54°
37°
23
50°
43°
24
50°
33°
25
47°
32°
26
48°
37°
27
48°
31°
28
47°
32°
29
47°
33°
30
49°
35°
1
50°
31°
2
53°
31°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
April Weather in Thunder Bay
Thunder Bay's April 2026 forecast shows daily high temperatures ranging from 32° to 54°, with overnight lows between 17° and 43°. The average high for April is 47° with an average low of 31°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how April weather will actually feel in Thunder Bay. See also: May | June | July.
