S
M
T
W
T
F
S
30
85°
56°
31
80°
55°
1
76°
56°
2
78°
62°
3
78°
56°
4
81°
63°
5
78°
62°
6
83°
57°
7
81°
55°
8
74°
54°
9
75°
54°
10
74°
60°
11
76°
53°
12
79°
53°
13
73°
52°
14
72°
58°
15
75°
60°
16
78°
50°
17
80°
50°
18
70°
49°
19
69°
50°
20
69°
50°
21
70°
51°
22
67°
51°
23
67°
52°
24
69°
53°
25
71°
52°
26
74°
55°
27
73°
51°
28
75°
46°
29
67°
46°
30
65°
51°
1
66°
52°
2
71°
53°
3
70°
51°
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 85°, with overnight lows between 46° 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 Watertown. See also: October | November | December.
