S
M
T
W
T
F
S
30
82°
72°
31
92°
74°
1
95°
73°
2
95°
73°
3
95°
73°
4
95°
72°
5
94°
74°
6
84°
70°
7
83°
66°
8
90°
66°
9
82°
68°
10
83°
61°
11
82°
56°
12
81°
60°
13
65°
55°
14
74°
55°
15
77°
65°
16
68°
62°
17
82°
67°
18
78°
71°
19
83°
64°
20
68°
58°
21
67°
51°
22
65°
45°
23
68°
48°
24
69°
51°
25
71°
53°
26
68°
51°
27
70°
50°
28
73°
52°
29
74°
51°
30
73°
50°
1
71°
46°
2
72°
52°
3
71°
52°
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 65° to 83°, with overnight lows between 45° and 71°. The average high for September is 71° 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.
