S
M
T
W
T
F
S
30
65°
56°
31
61°
56°
1
62°
55°
2
64°
55°
3
65°
57°
4
62°
55°
5
61°
54°
6
66°
57°
7
61°
55°
8
59°
53°
9
60°
51°
10
62°
55°
11
N/A
12
64°
52°
13
64°
58°
14
67°
54°
15
60°
53°
16
60°
52°
17
58°
52°
18
59°
51°
19
61°
52°
20
61°
52°
21
59°
51°
22
60°
51°
23
61°
52°
24
62°
51°
25
59°
50°
26
58°
51°
27
61°
51°
28
60°
49°
29
57°
49°
30
57°
51°
1
59°
50°
2
59°
49°
3
58°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Portstewart
Portstewart's September 2026 forecast shows daily high temperatures ranging from 57° to 67°, with overnight lows between 47° and 58°. The average high for September is 60° with an average low of 51°. 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 Portstewart. See also: October | November | December.
