S
M
T
W
T
F
S
30
87°
65°
31
86°
66°
1
82°
63°
2
81°
60°
3
81°
60°
4
82°
59°
5
81°
59°
6
84°
60°
7
83°
62°
8
84°
58°
9
81°
58°
10
82°
59°
11
85°
62°
12
84°
63°
13
85°
63°
14
85°
62°
15
84°
62°
16
84°
60°
17
83°
61°
18
83°
61°
19
82°
60°
20
81°
60°
21
82°
59°
22
82°
54°
23
76°
58°
24
75°
59°
25
Hist. Avg.
78°
56°
26
Hist. Avg.
78°
56°
27
Hist. Avg.
78°
55°
28
Hist. Avg.
77°
55°
29
Hist. Avg.
77°
54°
30
Hist. Avg.
77°
54°
1
Hist. Avg.
76°
54°
2
Hist. Avg.
76°
53°
3
Hist. Avg.
76°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Cardiff
Cardiff's September 2026 forecast shows daily high temperatures ranging from 75° to 87°, with overnight lows between 54° and 66°. The average high for September is 83° with an average low of 61°. 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.
