S
M
T
W
T
F
S
30
79°
59°
31
85°
51°
1
83°
58°
2
85°
57°
3
85°
53°
4
90°
48°
5
91°
57°
6
91°
48°
7
83°
52°
8
84°
40°
9
84°
36°
10
86°
62°
11
83°
44°
12
82°
50°
13
89°
51°
14
78°
41°
15
68°
47°
16
80°
46°
17
74°
48°
18
79°
47°
19
79°
46°
20
72°
48°
21
77°
45°
22
72°
44°
23
73°
41°
24
72°
47°
25
65°
44°
26
66°
44°
27
76°
47°
28
76°
46°
29
71°
45°
30
68°
39°
1
72°
45°
2
73°
44°
3
73°
45°
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 65° to 89°, with overnight lows between 39° and 62°. The average high for September is 75° with an average low of 46°. 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.
