S
M
T
W
T
F
S
30
85°
55°
31
84°
55°
1
79°
54°
2
81°
54°
3
82°
54°
4
78°
54°
5
81°
53°
6
81°
54°
7
85°
52°
8
85°
43°
9
79°
45°
10
73°
47°
11
78°
50°
12
80°
47°
13
80°
43°
14
73°
45°
15
78°
47°
16
80°
46°
17
80°
49°
18
81°
48°
19
81°
49°
20
80°
48°
21
80°
49°
22
81°
48°
23
80°
47°
24
78°
47°
25
78°
41°
26
73°
39°
27
63°
45°
28
73°
44°
29
75°
43°
30
70°
41°
1
76°
38°
2
67°
42°
3
73°
42°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Casper
Casper's September 2026 forecast shows daily high temperatures ranging from 63° to 85°, with overnight lows between 38° and 55°. The average high for September is 78° with an average low of 47°. 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 Casper. See also: October | November | December.
