S
M
T
W
T
F
S
30
96°
71°
31
92°
68°
1
91°
62°
2
88°
60°
3
87°
60°
4
88°
61°
5
94°
59°
6
76°
65°
7
90°
72°
8
101°
73°
9
110°
77°
10
104°
78°
11
98°
75°
12
95°
70°
13
91°
69°
14
91°
66°
15
89°
64°
16
86°
64°
17
87°
61°
18
90°
60°
19
92°
62°
20
88°
63°
21
86°
64°
22
88°
63°
23
89°
64°
24
87°
62°
25
88°
63°
26
92°
63°
27
93°
64°
28
86°
59°
29
86°
59°
30
84°
59°
1
83°
58°
2
81°
56°
3
81°
58°
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 81° to 93°, with overnight lows between 56° and 64°. The average high for September is 87° 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.
