S
M
T
W
T
F
S
30
98°
66°
31
97°
65°
1
98°
66°
2
98°
66°
3
92°
63°
4
93°
66°
5
97°
66°
6
96°
65°
7
97°
66°
8
94°
66°
9
92°
65°
10
92°
64°
11
92°
66°
12
97°
68°
13
98°
67°
14
99°
66°
15
96°
67°
16
95°
65°
17
97°
65°
18
97°
62°
19
91°
60°
20
87°
64°
21
89°
66°
22
94°
63°
23
89°
61°
24
86°
63°
25
87°
64°
26
92°
63°
27
92°
64°
28
90°
63°
29
84°
60°
30
82°
59°
1
83°
60°
2
83°
63°
3
88°
61°
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 82° to 99°, with overnight lows between 59° and 68°. The average high for September is 92° with an average low of 64°. 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.
