S
M
T
W
T
F
S
30
76°
51°
31
73°
49°
1
70°
48°
2
66°
48°
3
63°
59°
4
74°
58°
5
70°
58°
6
69°
52°
7
79°
48°
8
74°
44°
9
64°
60°
10
83°
55°
11
71°
46°
12
71°
52°
13
71°
57°
14
72°
50°
15
69°
55°
16
70°
50°
17
69°
49°
18
65°
48°
19
63°
45°
20
65°
44°
21
63°
46°
22
61°
51°
23
65°
50°
24
68°
50°
25
64°
49°
26
64°
47°
27
61°
45°
28
62°
45°
29
67°
48°
30
68°
49°
1
68°
49°
2
65°
48°
3
63°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Belfast
Belfast's September 2026 forecast shows daily high temperatures ranging from 61° to 83°, with overnight lows between 44° and 60°. The average high for September is 67° with an average low of 49°. 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 Belfast. See also: October | November | December.
