S
M
T
W
T
F
S
30
85°
54°
31
74°
55°
1
74°
62°
2
80°
61°
3
78°
54°
4
77°
59°
5
81°
52°
6
72°
53°
7
73°
54°
8
71°
50°
9
71°
54°
10
75°
53°
11
72°
49°
12
71°
50°
13
70°
49°
14
72°
54°
15
74°
49°
16
69°
48°
17
67°
47°
18
67°
46°
19
66°
47°
20
67°
49°
21
67°
52°
22
68°
48°
23
70°
55°
24
72°
50°
25
72°
56°
26
74°
54°
27
74°
46°
28
67°
46°
29
64°
53°
30
69°
54°
1
65°
53°
2
68°
52°
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 64° to 85°, with overnight lows between 45° and 62°. The average high for September is 71° with an average low of 52°. 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.
