S
M
T
W
T
F
S
29
50°
37°
30
46°
37°
1
57°
31°
2
50°
36°
3
50°
26°
4
60°
25°
5
53°
25°
6
43°
24°
7
44°
29°
8
45°
24°
9
44°
22°
10
42°
22°
11
39°
23°
12
39°
24°
13
41°
23°
14
41°
24°
15
42°
25°
16
42°
25°
17
43°
26°
18
42°
35°
19
46°
32°
20
46°
31°
21
42°
26°
22
42°
24°
23
41°
27°
24
42°
25°
25
40°
23°
26
39°
27°
27
39°
25°
28
40°
23°
29
39°
22°
30
38°
21°
31
37°
24°
1
37°
21°
2
Hist. Avg.
43°
26°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Herndon
Herndon's December 2026 forecast shows daily high temperatures ranging from 37° to 60°, with overnight lows between 21° and 37°. The average high for December is 44° with an average low of 26°. 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 Herndon. See also: January | February | March.
