S
M
T
W
T
F
S
26
85°
63°
27
82°
73°
28
81°
70°
29
72°
62°
30
66°
55°
1
67°
53°
2
73°
49°
3
79°
50°
4
81°
57°
5
75°
65°
6
74°
50°
7
69°
51°
8
77°
53°
9
84°
59°
10
80°
63°
11
76°
58°
12
80°
53°
13
82°
59°
14
81°
56°
15
91°
63°
16
87°
73°
17
90°
70°
18
90°
76°
19
87°
69°
20
76°
68°
21
75°
64°
22
76°
67°
23
76°
64°
24
82°
67°
25
81°
70°
26
78°
69°
27
85°
71°
28
80°
69°
29
80°
67°
30
81°
65°
31
80°
66°
1
81°
65°
2
78°
63°
3
81°
65°
4
82°
67°
5
85°
66°
6
86°
67°
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 78° to 86°, with overnight lows between 63° and 71°. The average high for May is 81° with an average low of 67°. 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.
