S
M
T
W
T
F
S
30
84°
52°
31
75°
51°
1
75°
51°
2
76°
57°
3
76°
51°
4
75°
58°
5
79°
58°
6
81°
52°
7
79°
50°
8
73°
50°
9
73°
49°
10
72°
55°
11
75°
49°
12
75°
49°
13
72°
48°
14
71°
54°
15
75°
55°
16
77°
46°
17
79°
45°
18
69°
45°
19
68°
46°
20
68°
46°
21
69°
47°
22
66°
45°
23
66°
49°
24
68°
50°
25
68°
49°
26
73°
51°
27
73°
46°
28
74°
42°
29
66°
42°
30
66°
48°
1
65°
49°
2
69°
48°
3
70°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Watertown
Watertown's September 2026 forecast shows daily high temperatures ranging from 65° to 84°, with overnight lows between 42° and 58°. The average high for September is 73° with an average low of 49°. 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 Watertown. See also: October | November | December.
