S
M
T
W
T
F
S
26
54°
40°
27
66°
40°
28
64°
41°
29
62°
45°
30
58°
46°
1
64°
42°
2
59°
46°
3
58°
42°
4
71°
48°
5
77°
51°
6
66°
53°
7
62°
46°
8
60°
43°
9
64°
48°
10
68°
50°
11
60°
47°
12
65°
40°
13
68°
46°
14
65°
51°
15
65°
47°
16
77°
46°
17
87°
62°
18
84°
62°
19
93°
64°
20
89°
64°
21
64°
54°
22
64°
52°
23
54°
49°
24
56°
49°
25
75°
55°
26
78°
54°
27
83°
60°
28
75°
55°
29
75°
57°
30
70°
49°
31
72°
51°
1
67°
51°
2
76°
52°
3
80°
56°
4
81°
56°
5
78°
59°
6
79°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Riverside
Riverside's May 2026 forecast shows daily high temperatures ranging from 67° to 83°, with overnight lows between 49° and 60°. The average high for May is 76° with an average low of 55°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Riverside. See also: June | July | August.