S
M
T
W
T
F
S
30
72°
65°
31
76°
56°
1
79°
63°
2
78°
68°
3
77°
60°
4
75°
52°
5
71°
51°
6
76°
59°
7
75°
57°
8
71°
56°
9
76°
63°
10
73°
58°
11
70°
59°
12
70°
55°
13
69°
56°
14
68°
53°
15
68°
58°
16
74°
57°
17
72°
53°
18
66°
49°
19
66°
49°
20
74°
57°
21
75°
58°
22
75°
58°
23
74°
56°
24
73°
54°
25
73°
55°
26
72°
56°
27
73°
55°
28
73°
53°
29
70°
49°
30
62°
45°
1
61°
48°
2
68°
53°
3
70°
52°
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 61° to 79°, with overnight lows between 45° and 68°. The average high for September is 72° with an average low of 55°. 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.
