S
M
T
W
T
F
S
30
65°
52°
31
61°
51°
1
64°
50°
2
71°
49°
3
72°
56°
4
60°
45°
5
68°
50°
6
56°
48°
7
58°
43°
8
57°
42°
9
59°
44°
10
60°
42°
11
53°
41°
12
54°
39°
13
55°
38°
14
52°
38°
15
54°
37°
16
53°
38°
17
50°
38°
18
50°
40°
19
49°
37°
20
49°
36°
21
48°
38°
22
48°
37°
23
47°
38°
24
48°
39°
25
48°
39°
26
47°
38°
27
47°
38°
28
48°
37°
29
46°
38°
30
47°
38°
1
46°
35°
2
45°
36°
3
44°
35°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Port O'Brien
Port O'Brien's September 2026 forecast shows daily high temperatures ranging from 44° to 72°, with overnight lows between 35° and 56°. The average high for September is 52° with an average low of 40°. 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 Port O'Brien. See also: October | November | December.
