S
M
T
W
T
F
S
26
45°
32°
27
52°
31°
28
55°
30°
29
58°
28°
30
62°
30°
1
66°
32°
2
70°
32°
3
74°
31°
4
75°
34°
5
62°
47°
6
64°
34°
7
72°
38°
8
76°
37°
9
73°
39°
10
76°
35°
11
85°
35°
12
86°
44°
13
87°
44°
14
70°
34°
15
75°
34°
16
66°
34°
17
49°
34°
18
54°
35°
19
63°
27°
20
68°
33°
21
65°
41°
22
70°
32°
23
80°
33°
24
83°
44°
25
72°
47°
26
69°
43°
27
72°
42°
28
72°
39°
29
64°
41°
30
67°
43°
31
72°
36°
1
79°
43°
2
78°
42°
3
79°
46°
4
76°
45°
5
75°
44°
6
76°
43°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in St. Charles
St. Charles's May 2026 forecast shows daily high temperatures ranging from 64° to 79°, with overnight lows between 36° and 47°. The average high for May is 73° with an average low of 43°. 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 St. Charles. See also: June | July | August.
