S
M
T
W
T
F
S
30
70°
50°
31
70°
50°
1
71°
48°
2
70°
50°
3
72°
48°
4
73°
52°
5
71°
53°
6
70°
49°
7
72°
47°
8
73°
53°
9
71°
46°
10
70°
46°
11
71°
52°
12
71°
51°
13
72°
43°
14
68°
53°
15
71°
54°
16
76°
51°
17
73°
43°
18
69°
41°
19
64°
41°
20
63°
42°
21
64°
41°
22
69°
49°
23
69°
47°
24
65°
41°
25
65°
39°
26
64°
40°
27
63°
40°
28
62°
39°
29
60°
39°
30
62°
46°
1
61°
41°
2
Hist. Avg.
66°
43°
3
Hist. Avg.
65°
43°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Waltham
Waltham's September 2026 forecast shows daily high temperatures ranging from 60° to 76°, with overnight lows between 39° and 54°. The average high for September is 68° with an average low of 46°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Waltham. See also: October | November | December.
