S
M
T
W
T
F
S
30
81°
69°
31
91°
72°
1
94°
77°
2
96°
78°
3
92°
79°
4
93°
78°
5
83°
73°
6
79°
71°
7
80°
64°
8
86°
72°
9
79°
66°
10
79°
61°
11
81°
63°
12
83°
67°
13
80°
64°
14
74°
63°
15
75°
60°
16
75°
62°
17
76°
61°
18
75°
62°
19
77°
58°
20
75°
57°
21
74°
62°
22
70°
61°
23
72°
61°
24
77°
60°
25
78°
62°
26
78°
61°
27
77°
62°
28
79°
62°
29
78°
61°
30
78°
61°
1
75°
56°
2
70°
50°
3
63°
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 63° to 86°, with overnight lows between 47° and 72°. The average high for September is 76° with an average low of 61°. 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.
