S
M
T
W
T
F
S
30
80°
55°
31
75°
52°
1
71°
53°
2
71°
52°
3
72°
51°
4
71°
52°
5
71°
51°
6
70°
52°
7
73°
57°
8
75°
57°
9
70°
51°
10
70°
52°
11
71°
54°
12
71°
51°
13
73°
53°
14
72°
54°
15
69°
50°
16
68°
49°
17
66°
48°
18
68°
52°
19
66°
53°
20
73°
53°
21
66°
53°
22
Hist. Avg.
69°
47°
23
Hist. Avg.
68°
46°
24
Hist. Avg.
68°
46°
25
Hist. Avg.
67°
46°
26
Hist. Avg.
67°
46°
27
Hist. Avg.
66°
45°
28
Hist. Avg.
66°
45°
29
Hist. Avg.
66°
44°
30
Hist. Avg.
65°
44°
1
Hist. Avg.
65°
44°
2
Hist. Avg.
64°
44°
3
Hist. Avg.
64°
43°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Watertown
Watertown's September 2026 forecast shows daily high temperatures ranging from 66° to 80°, with overnight lows between 48° and 57°. The average high for September is 71° with an average low of 52°. 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.
