S
M
T
W
T
F
S
30
68°
65°
31
76°
68°
1
88°
69°
2
94°
70°
3
80°
63°
4
75°
63°
5
75°
60°
6
75°
56°
7
77°
56°
8
81°
68°
9
87°
62°
10
70°
54°
11
74°
60°
12
78°
61°
13
74°
58°
14
74°
55°
15
72°
54°
16
75°
55°
17
76°
50°
18
69°
58°
19
75°
60°
20
76°
61°
21
76°
61°
22
74°
59°
23
71°
58°
24
69°
59°
25
73°
59°
26
72°
57°
27
63°
53°
28
63°
53°
29
64°
51°
30
62°
49°
1
60°
50°
2
61°
55°
3
67°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Sarnia
Sarnia's September 2026 forecast shows daily high temperatures ranging from 60° to 87°, with overnight lows between 49° and 68°. The average high for September is 72° with an average low of 57°. 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 Sarnia. See also: October | November | December.
