S
M
T
W
T
F
S
30
77°
56°
31
77°
60°
1
75°
60°
2
71°
60°
3
80°
63°
4
80°
62°
5
74°
57°
6
69°
52°
7
75°
48°
8
76°
52°
9
78°
57°
10
82°
61°
11
74°
54°
12
75°
49°
13
73°
64°
14
69°
49°
15
69°
46°
16
74°
52°
17
80°
65°
18
79°
51°
19
67°
52°
20
61°
56°
21
67°
52°
22
62°
44°
23
65°
45°
24
65°
49°
25
68°
48°
26
72°
46°
27
70°
50°
28
70°
51°
29
72°
50°
30
71°
43°
1
65°
45°
2
71°
48°
3
64°
48°
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 80°, with overnight lows between 43° and 65°. The average high for September is 69° 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.
