S
M
T
W
T
F
S
30
82°
59°
31
82°
61°
1
81°
62°
2
81°
59°
3
80°
52°
4
73°
50°
5
72°
56°
6
74°
61°
7
80°
60°
8
80°
59°
9
76°
52°
10
75°
59°
11
78°
58°
12
78°
60°
13
79°
60°
14
78°
59°
15
78°
56°
16
77°
54°
17
72°
55°
18
76°
50°
19
68°
48°
20
68°
47°
21
65°
46°
22
66°
55°
23
67°
51°
24
67°
46°
25
65°
46°
26
65°
53°
27
71°
54°
28
72°
52°
29
73°
49°
30
68°
49°
1
63°
50°
2
70°
44°
3
63°
46°
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 82°, with overnight lows between 44° and 62°. The average high for September is 73° 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.
