S
M
T
W
T
F
S
30
66°
47°
31
67°
49°
1
69°
55°
2
74°
57°
3
69°
59°
4
71°
59°
5
78°
56°
6
74°
50°
7
67°
47°
8
67°
47°
9
71°
46°
10
73°
51°
11
72°
50°
12
64°
52°
13
71°
55°
14
74°
54°
15
74°
53°
16
69°
52°
17
64°
53°
18
69°
52°
19
68°
48°
20
63°
51°
21
70°
42°
22
63°
40°
23
61°
40°
24
60°
42°
25
64°
41°
26
59°
39°
27
59°
40°
28
60°
42°
29
57°
38°
30
58°
42°
1
58°
40°
2
62°
37°
3
55°
38°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Saint-Joseph-du-Lac
Saint-Joseph-du-Lac's September 2026 forecast shows daily high temperatures ranging from 55° to 78°, with overnight lows between 37° and 59°. The average high for September is 66° with an average low of 48°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Saint-Joseph-du-Lac. See also: October | November | December.