S
M
T
W
T
F
S
29
40°
25°
30
37°
23°
1
28°
22°
2
29°
15°
3
29°
22°
4
35°
22°
5
32°
21°
6
29°
16°
7
22°
10°
8
22°
13°
9
27°
16°
10
34°
20°
11
34°
19°
12
33°
18°
13
32°
19°
14
21°
18°
15
30°
15°
16
30°
12°
17
26°
13°
18
27°
12°
19
26°
6°
20
23°
2°
21
19°
14°
22
28°
12°
23
29°
12°
24
27°
7°
25
27°
8°
26
22°
14°
27
26°
15°
28
30°
14°
29
29°
9°
30
27°
7°
31
25°
-2°
1
26°
-5°
2
14°
1°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Waltham
Waltham's December 2026 forecast shows daily high temperatures ranging from 14° to 40°, with overnight lows between -5° and 25°. The average high for December is 28° with an average low of 13°. 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 Waltham. See also: January | February | March.
