S
M
T
W
T
F
S
30
84°
57°
31
85°
60°
1
86°
61°
2
87°
62°
3
87°
61°
4
81°
60°
5
82°
59°
6
80°
56°
7
83°
59°
8
87°
61°
9
87°
60°
10
86°
61°
11
86°
61°
12
85°
60°
13
86°
60°
14
83°
59°
15
82°
59°
16
83°
58°
17
82°
59°
18
80°
56°
19
76°
55°
20
75°
56°
21
75°
54°
22
77°
49°
23
74°
48°
24
74°
55°
25
81°
54°
26
80°
55°
27
72°
56°
28
72°
55°
29
73°
54°
30
73°
49°
1
71°
44°
2
70°
43°
3
68°
43°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in New Castle
New Castle's September 2026 forecast shows daily high temperatures ranging from 68° to 87°, with overnight lows between 43° and 62°. The average high for September is 80° with an average low of 56°. 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 New Castle. See also: October | November | December.
