S
M
T
W
T
F
S
30
89°
72°
31
91°
73°
1
94°
73°
2
94°
72°
3
93°
73°
4
94°
73°
5
94°
72°
6
93°
71°
7
94°
69°
8
93°
70°
9
92°
70°
10
93°
68°
11
95°
70°
12
94°
68°
13
94°
70°
14
95°
69°
15
94°
69°
16
92°
68°
17
85°
68°
18
87°
67°
19
86°
67°
20
86°
68°
21
91°
66°
22
88°
63°
23
90°
66°
24
87°
65°
25
86°
65°
26
89°
66°
27
90°
65°
28
89°
63°
29
82°
62°
30
81°
59°
1
80°
58°
2
81°
59°
3
82°
60°
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 80° to 95°, with overnight lows between 58° and 73°. The average high for September is 90° with an average low of 67°. 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.
