S
M
T
W
T
F
S
30
78°
55°
31
75°
52°
1
72°
53°
2
72°
51°
3
71°
52°
4
72°
52°
5
71°
53°
6
71°
54°
7
72°
59°
8
72°
54°
9
71°
52°
10
71°
51°
11
72°
52°
12
70°
53°
13
71°
54°
14
70°
53°
15
69°
55°
16
71°
50°
17
70°
49°
18
70°
50°
19
76°
52°
20
Hist. Avg.
70°
51°
21
Hist. Avg.
69°
50°
22
Hist. Avg.
69°
50°
23
Hist. Avg.
69°
50°
24
Hist. Avg.
69°
50°
25
Hist. Avg.
68°
49°
26
Hist. Avg.
68°
49°
27
Hist. Avg.
68°
49°
28
Hist. Avg.
67°
49°
29
Hist. Avg.
67°
48°
30
Hist. Avg.
67°
48°
1
Hist. Avg.
66°
48°
2
Hist. Avg.
66°
47°
3
Hist. Avg.
66°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in St. Catharines
St. Catharines's September 2026 forecast shows daily high temperatures ranging from 69° to 78°, with overnight lows between 49° and 59°. The average high for September is 72° with an average low of 53°. 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.
