S
M
T
W
T
F
S
26
60°
40°
27
58°
38°
28
54°
34°
29
60°
35°
30
55°
34°
1
57°
34°
2
55°
37°
3
57°
39°
4
55°
36°
5
55°
36°
6
58°
37°
7
64°
38°
8
60°
37°
9
59°
38°
10
58°
37°
11
58°
37°
12
61°
49°
13
68°
44°
14
60°
47°
15
68°
47°
16
63°
44°
17
65°
46°
18
69°
51°
19
72°
54°
20
71°
49°
21
68°
47°
22
65°
47°
23
66°
45°
24
65°
46°
25
70°
47°
26
74°
55°
27
77°
48°
28
78°
53°
29
70°
51°
30
75°
53°
31
76°
47°
1
71°
46°
2
69°
44°
3
67°
47°
4
69°
49°
5
71°
54°
6
72°
49°
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 54° to 78°, with overnight lows between 34° and 55°. The average high for May is 65° with an average low of 44°. 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.
