S
M
T
W
T
F
S
30
71°
54°
31
63°
52°
1
63°
48°
2
62°
49°
3
61°
43°
4
61°
47°
5
59°
48°
6
61°
47°
7
60°
40°
8
58°
42°
9
60°
38°
10
59°
41°
11
57°
39°
12
58°
40°
13
56°
39°
14
61°
41°
15
68°
48°
16
69°
49°
17
70°
49°
18
70°
48°
19
71°
50°
20
70°
51°
21
67°
49°
22
68°
48°
23
65°
40°
24
61°
40°
25
65°
45°
26
63°
44°
27
62°
44°
28
62°
40°
29
60°
42°
30
62°
43°
1
63°
44°
2
62°
43°
3
64°
35°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Westmount
Westmount's September 2026 forecast shows daily high temperatures ranging from 56° to 71°, with overnight lows between 35° and 54°. The average high for September is 63° with an average low of 45°. 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 Westmount. See also: October | November | December.