S
M
T
W
T
F
S
30
77°
61°
31
78°
60°
1
77°
61°
2
76°
59°
3
76°
58°
4
77°
60°
5
79°
64°
6
76°
63°
7
75°
60°
8
80°
57°
9
75°
62°
10
78°
66°
11
81°
64°
12
82°
64°
13
81°
56°
14
76°
62°
15
74°
55°
16
73°
55°
17
71°
62°
18
77°
57°
19
75°
60°
20
72°
53°
21
78°
52°
22
69°
50°
23
76°
60°
24
77°
61°
25
Hist. Avg.
73°
55°
26
Hist. Avg.
73°
55°
27
Hist. Avg.
72°
54°
28
Hist. Avg.
72°
54°
29
Hist. Avg.
71°
53°
30
Hist. Avg.
71°
53°
1
Hist. Avg.
70°
53°
2
Hist. Avg.
70°
52°
3
Hist. Avg.
70°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Riverside
Riverside's September 2026 forecast shows daily high temperatures ranging from 69° to 82°, with overnight lows between 50° and 66°. The average high for September is 76° with an average low of 59°. 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.
