S
M
T
W
T
F
S
26
64°
50°
27
69°
47°
28
78°
52°
29
72°
53°
30
73°
54°
1
79°
57°
2
79°
56°
3
74°
55°
4
69°
54°
5
72°
57°
6
77°
56°
7
77°
57°
8
80°
57°
9
79°
55°
10
81°
57°
11
81°
57°
12
82°
58°
13
82°
59°
14
83°
59°
15
83°
58°
16
82°
59°
17
80°
57°
18
79°
54°
19
77°
54°
20
77°
55°
21
79°
55°
22
79°
56°
23
82°
59°
24
83°
60°
25
84°
60°
26
83°
61°
27
85°
61°
28
85°
60°
29
84°
61°
30
84°
61°
31
81°
58°
1
81°
56°
2
82°
56°
3
81°
54°
4
78°
54°
5
78°
55°
6
79°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Rancho Cucamonga
Rancho Cucamonga's May 2026 forecast shows daily high temperatures ranging from 64° to 85°, with overnight lows between 47° and 61°. The average high for May is 79° with an average low of 56°. 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 Rancho Cucamonga. See also: June | July | August.
