S
M
T
W
T
F
S
30
86°
54°
31
77°
53°
1
77°
55°
2
80°
60°
3
76°
53°
4
76°
61°
5
81°
59°
6
82°
53°
7
79°
52°
8
75°
51°
9
74°
50°
10
74°
57°
11
76°
50°
12
74°
50°
13
73°
49°
14
74°
57°
15
78°
56°
16
77°
48°
17
78°
47°
18
70°
46°
19
69°
47°
20
69°
48°
21
70°
49°
22
67°
47°
23
68°
52°
24
72°
52°
25
72°
51°
26
75°
53°
27
74°
48°
28
73°
43°
29
66°
43°
30
66°
51°
1
65°
52°
2
69°
51°
3
72°
49°
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 86°, with overnight lows between 43° and 61°. The average high for September is 74° with an average low of 51°. 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.
