S
M
T
W
T
F
S
30
85°
63°
31
90°
68°
1
92°
69°
2
92°
70°
3
92°
71°
4
93°
71°
5
89°
67°
6
78°
60°
7
81°
58°
8
86°
60°
9
89°
68°
10
81°
68°
11
80°
62°
12
80°
67°
13
85°
61°
14
72°
54°
15
90°
55°
16
90°
70°
17
89°
68°
18
76°
67°
19
84°
67°
20
85°
68°
21
68°
56°
22
64°
55°
23
62°
58°
24
66°
52°
25
N/A
26
71°
42°
27
73°
47°
28
74°
49°
29
74°
58°
30
74°
58°
1
79°
57°
2
72°
56°
3
74°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in New Castle
New Castle's September 2026 forecast shows daily high temperatures ranging from 71° to 79°, with overnight lows between 42° and 58°. The average high for September is 74° with an average low of 53°. 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.
