S
M
T
W
T
F
S
30
74°
51°
31
72°
48°
1
77°
46°
2
71°
53°
3
77°
59°
4
74°
56°
5
69°
54°
6
69°
49°
7
75°
43°
8
70°
42°
9
67°
41°
10
71°
49°
11
63°
43°
12
74°
40°
13
76°
56°
14
59°
37°
15
65°
53°
16
73°
52°
17
67°
55°
18
66°
42°
19
65°
47°
20
64°
44°
21
60°
45°
22
62°
46°
23
61°
46°
24
67°
48°
25
67°
47°
26
63°
48°
27
57°
46°
28
66°
44°
29
60°
40°
30
59°
37°
1
63°
45°
2
63°
45°
3
64°
43°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Castlebar
Castlebar's September 2026 forecast shows daily high temperatures ranging from 57° to 73°, with overnight lows between 37° and 55°. The average high for September is 64° with an average low of 46°. 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 Castlebar. See also: October | November | December.
