S
M
T
W
T
F
S
30
93°
57°
31
85°
60°
1
78°
59°
2
93°
66°
3
93°
64°
4
96°
67°
5
93°
68°
6
82°
64°
7
86°
65°
8
84°
57°
9
78°
56°
10
77°
57°
11
76°
53°
12
70°
57°
13
75°
58°
14
82°
60°
15
78°
59°
16
80°
59°
17
82°
58°
18
76°
57°
19
74°
57°
20
79°
56°
21
78°
56°
22
77°
55°
23
78°
58°
24
78°
57°
25
77°
56°
26
75°
55°
27
76°
56°
28
76°
56°
29
75°
55°
30
74°
54°
1
74°
54°
2
73°
53°
3
72°
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 70° to 96°, with overnight lows between 52° and 68°. The average high for September is 79° with an average low of 58°. 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.
