S
M
T
W
T
F
S
30
83°
55°
31
79°
56°
1
70°
60°
2
71°
63°
3
78°
61°
4
83°
59°
5
74°
53°
6
71°
52°
7
76°
57°
8
75°
56°
9
79°
58°
10
76°
57°
11
75°
55°
12
77°
54°
13
75°
52°
14
73°
53°
15
71°
55°
16
73°
56°
17
77°
55°
18
69°
52°
19
70°
53°
20
71°
55°
21
75°
56°
22
77°
56°
23
77°
55°
24
76°
54°
25
75°
53°
26
76°
53°
27
75°
54°
28
75°
52°
29
74°
51°
30
67°
47°
1
64°
47°
2
64°
51°
3
71°
51°
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 64° to 83°, with overnight lows between 47° and 63°. The average high for September is 74° with an average low of 54°. 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.
