S
M
T
W
T
F
S
30
95°
78°
31
93°
77°
1
93°
78°
2
94°
77°
3
94°
77°
4
93°
76°
5
95°
78°
6
95°
78°
7
96°
77°
8
96°
78°
9
94°
77°
10
94°
76°
11
95°
77°
12
93°
78°
13
94°
75°
14
92°
73°
15
90°
72°
16
91°
72°
17
90°
73°
18
91°
73°
19
93°
76°
20
92°
75°
21
90°
71°
22
88°
72°
23
Hist. Avg.
91°
74°
24
Hist. Avg.
91°
73°
25
Hist. Avg.
91°
73°
26
Hist. Avg.
91°
73°
27
Hist. Avg.
90°
73°
28
Hist. Avg.
90°
73°
29
Hist. Avg.
90°
72°
30
Hist. Avg.
90°
72°
1
Hist. Avg.
90°
72°
2
Hist. Avg.
90°
72°
3
Hist. Avg.
90°
72°
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 88° to 96°, with overnight lows between 71° and 78°. The average high for September is 93° with an average low of 76°. 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.
