S
M
T
W
T
F
S
30
77°
66°
31
77°
65°
1
80°
64°
2
78°
63°
3
77°
62°
4
77°
63°
5
73°
58°
6
67°
55°
7
74°
61°
8
75°
60°
9
75°
60°
10
69°
59°
11
72°
59°
12
74°
58°
13
74°
59°
14
73°
59°
15
74°
58°
16
73°
57°
17
69°
58°
18
74°
58°
19
70°
57°
20
72°
58°
21
72°
59°
22
73°
58°
23
73°
56°
24
65°
55°
25
62°
52°
26
64°
54°
27
67°
54°
28
69°
55°
29
70°
55°
30
70°
54°
1
69°
54°
2
69°
54°
3
67°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Clarington
Clarington's September 2026 forecast shows daily high temperatures ranging from 62° to 80°, with overnight lows between 52° and 66°. The average high for September is 72° with an average low of 58°. 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 Clarington. See also: October | November | December.