S
M
T
W
T
F
S
30
88°
54°
31
85°
52°
1
76°
56°
2
73°
60°
3
83°
59°
4
84°
50°
5
75°
51°
6
74°
58°
7
82°
58°
8
83°
49°
9
74°
54°
10
72°
55°
11
72°
48°
12
70°
49°
13
70°
51°
14
71°
55°
15
77°
56°
16
78°
56°
17
81°
55°
18
77°
48°
19
69°
52°
20
73°
53°
21
70°
52°
22
73°
44°
23
65°
44°
24
63°
43°
25
68°
47°
26
73°
49°
27
Hist. Avg.
70°
42°
28
Hist. Avg.
70°
42°
29
Hist. Avg.
69°
41°
30
Hist. Avg.
69°
41°
1
Hist. Avg.
68°
40°
2
Hist. Avg.
68°
40°
3
Hist. Avg.
67°
39°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Rapid City
Rapid City's September 2026 forecast shows daily high temperatures ranging from 63° to 88°, with overnight lows between 43° and 60°. The average high for September is 75° with an average low of 52°. 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.
