S
M
T
W
T
F
S
30
83°
54°
31
79°
66°
1
92°
69°
2
76°
67°
3
88°
67°
4
85°
67°
5
80°
58°
6
78°
51°
7
77°
50°
8
80°
60°
9
84°
69°
10
81°
59°
11
74°
50°
12
76°
55°
13
79°
57°
14
80°
53°
15
72°
50°
16
74°
52°
17
71°
53°
18
74°
50°
19
72°
48°
20
77°
53°
21
77°
55°
22
70°
54°
23
71°
53°
24
72°
53°
25
73°
52°
26
76°
51°
27
73°
47°
28
74°
52°
29
75°
53°
30
76°
52°
1
75°
51°
2
73°
50°
3
72°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Riverside
Riverside's September 2026 forecast shows daily high temperatures ranging from 70° to 84°, with overnight lows between 47° and 69°. The average high for September is 75° with an average low of 53°. 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 Riverside. See also: October | November | December.
