S
M
T
W
T
F
S
30
84°
59°
31
79°
55°
1
76°
54°
2
76°
54°
3
75°
53°
4
76°
56°
5
77°
61°
6
78°
62°
7
80°
61°
8
82°
59°
9
83°
59°
10
81°
60°
11
84°
60°
12
83°
59°
13
82°
60°
14
80°
56°
15
82°
48°
16
74°
48°
17
72°
49°
18
72°
49°
19
73°
52°
20
72°
56°
21
74°
55°
22
71°
54°
23
77°
56°
24
78°
55°
25
78°
55°
26
79°
54°
27
78°
52°
28
77°
44°
29
75°
44°
30
66°
48°
1
65°
46°
2
67°
50°
3
65°
45°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Somerville
Somerville's September 2026 forecast shows daily high temperatures ranging from 65° to 84°, with overnight lows between 44° and 62°. The average high for September is 76° 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 Somerville. See also: October | November | December.