S
M
T
W
T
F
S
29
43°
34°
30
45°
36°
1
47°
36°
2
46°
35°
3
47°
32°
4
33°
30°
5
43°
28°
6
51°
27°
7
37°
25°
8
35°
21°
9
36°
20°
10
31°
18°
11
31°
18°
12
32°
22°
13
32°
24°
14
34°
25°
15
35°
29°
16
38°
28°
17
45°
23°
18
45°
23°
19
33°
22°
20
33°
19°
21
35°
18°
22
30°
17°
23
31°
19°
24
35°
27°
25
37°
31°
26
43°
30°
27
47°
29°
28
46°
26°
29
36°
25°
30
36°
26°
31
37°
24°
1
39°
21°
2
36°
22°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Williamsport
Williamsport's December 2026 forecast shows daily high temperatures ranging from 30° to 51°, with overnight lows between 17° and 36°. The average high for December is 38° with an average low of 25°. 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 Williamsport. See also: January | February | March.
