S
M
T
W
T
F
S
29
37°
29°
30
37°
25°
1
36°
23°
2
36°
26°
3
37°
30°
4
40°
29°
5
40°
32°
6
42°
32°
7
38°
33°
8
35°
31°
9
36°
27°
10
33°
28°
11
44°
28°
12
42°
30°
13
37°
30°
14
38°
24°
15
36°
21°
16
32°
27°
17
34°
29°
18
36°
29°
19
36°
31°
20
37°
31°
21
38°
30°
22
41°
31°
23
42°
35°
24
45°
30°
25
45°
24°
26
44°
25°
27
31°
20°
28
32°
26°
29
33°
29°
30
41°
30°
31
42°
32°
1
42°
30°
2
44°
27°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in St. Catharines
St. Catharines's December 2026 forecast shows daily high temperatures ranging from 31° to 45°, with overnight lows between 20° and 35°. The average high for December is 38° with an average low of 28°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how December weather will actually feel in St. Catharines. See also: January | February | March.
