S
M
T
W
T
F
S
26
89°
70°
27
89°
75°
28
93°
77°
29
84°
64°
30
76°
61°
1
65°
54°
2
75°
50°
3
80°
50°
4
82°
57°
5
85°
69°
6
85°
63°
7
70°
60°
8
80°
62°
9
90°
71°
10
89°
65°
11
83°
64°
12
85°
61°
13
90°
60°
14
90°
61°
15
91°
68°
16
90°
68°
17
89°
74°
18
92°
77°
19
92°
67°
20
85°
67°
21
82°
66°
22
88°
64°
23
82°
65°
24
89°
65°
25
90°
67°
26
87°
70°
27
78°
69°
28
88°
70°
29
92°
73°
30
90°
72°
31
89°
69°
1
86°
70°
2
89°
69°
3
87°
69°
4
88°
69°
5
92°
72°
6
91°
71°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in San Marcos
San Marcos's May 2026 forecast shows daily high temperatures ranging from 78° to 92°, with overnight lows between 65° and 73°. The average high for May is 88° with an average low of 70°. 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 San Marcos. See also: June | July | August.
