S
M
T
W
T
F
S
30
75°
63°
31
86°
67°
1
82°
71°
2
77°
63°
3
75°
61°
4
79°
62°
5
78°
61°
6
78°
58°
7
73°
56°
8
72°
55°
9
73°
59°
10
71°
57°
11
68°
52°
12
69°
54°
13
68°
56°
14
71°
51°
15
75°
58°
16
75°
56°
17
71°
56°
18
70°
55°
19
74°
57°
20
74°
57°
21
73°
56°
22
75°
57°
23
74°
56°
24
73°
56°
25
74°
55°
26
74°
56°
27
73°
55°
28
73°
54°
29
70°
53°
30
69°
53°
1
70°
54°
2
70°
53°
3
70°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Rapid City
Rapid City's September 2026 forecast shows daily high temperatures ranging from 68° to 82°, with overnight lows between 51° and 71°. The average high for September is 73° with an average low of 57°. 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 Rapid City. See also: October | November | December.
