S
M
T
W
T
F
S
30
69°
46°
31
73°
53°
1
72°
55°
2
74°
54°
3
70°
49°
4
68°
46°
5
67°
44°
6
67°
45°
7
69°
51°
8
70°
47°
9
65°
44°
10
66°
43°
11
68°
39°
12
63°
41°
13
65°
42°
14
64°
41°
15
63°
40°
16
64°
39°
17
63°
39°
18
67°
43°
19
61°
40°
20
63°
38°
21
61°
37°
22
62°
39°
23
67°
42°
24
67°
37°
25
68°
43°
26
70°
45°
27
69°
43°
28
60°
38°
29
65°
38°
30
65°
34°
1
58°
42°
2
67°
44°
3
68°
34°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Londonderry
Londonderry's September 2026 forecast shows daily high temperatures ranging from 58° to 74°, with overnight lows between 34° and 55°. The average high for September is 66° with an average low of 43°. 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 Londonderry. See also: October | November | December.
