S
M
T
W
T
F
S
30
83°
55°
31
79°
56°
1
70°
59°
2
75°
59°
3
77°
61°
4
84°
60°
5
73°
56°
6
71°
50°
7
80°
47°
8
79°
52°
9
80°
52°
10
85°
67°
11
76°
49°
12
78°
42°
13
71°
62°
14
73°
47°
15
71°
40°
16
79°
48°
17
82°
61°
18
78°
58°
19
66°
47°
20
63°
56°
21
66°
47°
22
62°
48°
23
62°
49°
24
63°
49°
25
61°
51°
26
66°
49°
27
69°
49°
28
68°
51°
29
67°
50°
30
68°
52°
1
67°
50°
2
68°
48°
3
64°
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 69°, with overnight lows between 47° and 56°. The average high for September is 65° with an average low of 50°. 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.
