S
M
T
W
T
F
S
26
49°
38°
27
63°
42°
28
64°
45°
29
51°
41°
30
N/A
1
49°
35°
2
48°
34°
3
54°
47°
4
61°
50°
5
58°
43°
6
53°
39°
7
49°
36°
8
52°
41°
9
52°
41°
10
57°
45°
11
57°
45°
12
56°
44°
13
57°
46°
14
56°
45°
15
61°
43°
16
60°
44°
17
61°
48°
18
64°
52°
19
67°
52°
20
67°
51°
21
70°
53°
22
68°
50°
23
65°
53°
24
69°
47°
25
63°
46°
26
65°
54°
27
65°
54°
28
71°
55°
29
69°
54°
30
67°
52°
31
69°
47°
1
65°
49°
2
65°
49°
3
66°
48°
4
66°
50°
5
67°
51°
6
67°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in St. Catharines
St. Catharines's May 2026 forecast shows daily high temperatures ranging from 48° to 71°, with overnight lows between 34° and 55°. The average high for May is 62° with an average low of 47°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in St. Catharines. See also: June | July | August.
