S
M
T
W
T
F
S
30
80°
53°
31
78°
53°
1
78°
54°
2
80°
57°
3
78°
54°
4
80°
54°
5
81°
53°
6
80°
52°
7
78°
50°
8
79°
51°
9
78°
58°
10
78°
51°
11
77°
50°
12
77°
50°
13
79°
56°
14
81°
52°
15
81°
56°
16
83°
56°
17
84°
55°
18
82°
55°
19
82°
54°
20
81°
47°
21
73°
52°
22
73°
54°
23
77°
53°
24
79°
54°
25
80°
49°
26
78°
44°
27
74°
45°
28
69°
44°
29
68°
45°
30
68°
43°
1
Hist. Avg.
73°
47°
2
Hist. Avg.
72°
46°
3
Hist. Avg.
72°
46°
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 84°, with overnight lows between 43° and 58°. The average high for September is 78° with an average low of 52°. 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.
