S
M
T
W
T
F
S
30
73°
53°
31
74°
61°
1
76°
62°
2
73°
63°
3
78°
63°
4
82°
58°
5
83°
57°
6
73°
52°
7
71°
52°
8
73°
59°
9
76°
55°
10
78°
58°
11
75°
54°
12
73°
59°
13
74°
58°
14
79°
54°
15
70°
57°
16
68°
56°
17
67°
57°
18
68°
51°
19
74°
50°
20
68°
54°
21
72°
47°
22
68°
50°
23
67°
47°
24
70°
49°
25
72°
53°
26
71°
50°
27
68°
56°
28
67°
50°
29
71°
45°
30
63°
53°
1
69°
48°
2
72°
46°
3
65°
45°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St. Catharines
St. Catharines's September 2026 forecast shows daily high temperatures ranging from 63° to 83°, with overnight lows between 45° and 63°. The average high for September 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 September weather will actually feel in St. Catharines. See also: October | November | December.
