S
M
T
W
T
F
S
30
87°
58°
31
87°
60°
1
86°
61°
2
86°
60°
3
86°
52°
4
79°
51°
5
78°
54°
6
81°
59°
7
85°
60°
8
85°
58°
9
80°
53°
10
79°
58°
11
84°
57°
12
83°
59°
13
84°
58°
14
84°
58°
15
83°
57°
16
83°
56°
17
78°
54°
18
82°
50°
19
74°
47°
20
74°
46°
21
71°
45°
22
72°
52°
23
74°
49°
24
74°
45°
25
71°
45°
26
72°
52°
27
77°
51°
28
78°
52°
29
77°
51°
30
77°
51°
1
71°
50°
2
75°
49°
3
69°
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 69° to 87°, with overnight lows between 45° and 61°. The average high for September is 79° 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.
