S
M
T
W
T
F
S
30
71°
55°
31
68°
55°
1
68°
59°
2
67°
63°
3
71°
62°
4
71°
56°
5
70°
56°
6
67°
55°
7
69°
57°
8
68°
55°
9
69°
53°
10
67°
54°
11
65°
52°
12
66°
49°
13
65°
50°
14
66°
50°
15
66°
52°
16
63°
48°
17
63°
53°
18
64°
53°
19
66°
52°
20
64°
52°
21
66°
53°
22
65°
53°
23
66°
49°
24
62°
46°
25
63°
46°
26
63°
48°
27
64°
49°
28
64°
50°
29
65°
51°
30
65°
51°
1
64°
50°
2
65°
51°
3
64°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Cardiff
Cardiff's September 2026 forecast shows daily high temperatures ranging from 62° to 71°, with overnight lows between 46° and 63°. The average high for September is 66° with an average low of 53°. 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 Cardiff. See also: October | November | December.
