S
M
T
W
T
F
S
29
64°
51°
30
69°
48°
1
72°
39°
2
63°
42°
3
64°
39°
4
61°
35°
5
60°
37°
6
61°
43°
7
67°
49°
8
65°
51°
9
69°
51°
10
71°
45°
11
73°
45°
12
65°
46°
13
Hist. Avg.
63°
40°
14
Hist. Avg.
63°
40°
15
Hist. Avg.
63°
40°
16
Hist. Avg.
63°
40°
17
Hist. Avg.
63°
40°
18
Hist. Avg.
63°
40°
19
Hist. Avg.
62°
39°
20
Hist. Avg.
62°
39°
21
Hist. Avg.
62°
39°
22
Hist. Avg.
62°
39°
23
Hist. Avg.
62°
39°
24
Hist. Avg.
62°
39°
25
Hist. Avg.
62°
39°
26
Hist. Avg.
62°
39°
27
Hist. Avg.
62°
39°
28
Hist. Avg.
62°
39°
29
Hist. Avg.
62°
38°
30
Hist. Avg.
62°
38°
31
Hist. Avg.
62°
38°
1
Hist. Avg.
62°
38°
2
Hist. Avg.
62°
38°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
December Weather in San Marcos
San Marcos's December 2026 forecast shows daily high temperatures ranging from 60° to 73°, with overnight lows between 35° and 51°. The average high for December is 66° 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 December weather will actually feel in San Marcos. See also: January | February | March.
