S
M
T
W
T
F
S
30
87°
65°
31
87°
64°
1
86°
67°
2
86°
64°
3
90°
68°
4
90°
65°
5
89°
68°
6
90°
67°
7
86°
67°
8
88°
65°
9
89°
66°
10
85°
66°
11
88°
65°
12
88°
66°
13
87°
65°
14
87°
65°
15
86°
64°
16
87°
65°
17
87°
63°
18
86°
63°
19
85°
62°
20
85°
58°
21
81°
61°
22
80°
62°
23
84°
61°
24
84°
60°
25
83°
60°
26
85°
59°
27
83°
60°
28
83°
60°
29
82°
59°
30
83°
57°
1
81°
58°
2
83°
59°
3
83°
59°
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 80° to 90°, with overnight lows between 57° and 68°. The average high for September is 86° with an average low of 63°. 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.
