S
M
T
W
T
F
S
30
75°
52°
31
75°
49°
1
76°
55°
2
75°
54°
3
81°
62°
4
76°
59°
5
71°
54°
6
74°
51°
7
80°
51°
8
73°
52°
9
71°
52°
10
73°
55°
11
67°
50°
12
76°
46°
13
78°
64°
14
67°
45°
15
65°
40°
16
78°
55°
17
70°
53°
18
69°
44°
19
63°
38°
20
64°
44°
21
61°
42°
22
64°
39°
23
69°
43°
24
72°
42°
25
76°
43°
26
74°
51°
27
N/A
28
57°
51°
29
67°
50°
30
69°
58°
1
73°
57°
2
68°
46°
3
62°
41°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Longueuil
Longueuil's September 2026 forecast shows daily high temperatures ranging from 57° to 73°, with overnight lows between 41° and 58°. The average high for September is 66° with an average low of 51°. 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 Longueuil. See also: October | November | December.
