S
M
T
W
T
F
S
30
71°
58°
31
70°
61°
1
79°
66°
2
83°
65°
3
80°
65°
4
76°
60°
5
74°
56°
6
72°
52°
7
73°
60°
8
74°
66°
9
78°
69°
10
74°
59°
11
67°
54°
12
78°
64°
13
76°
63°
14
73°
63°
15
75°
62°
16
70°
58°
17
68°
55°
18
70°
59°
19
69°
58°
20
65°
45°
21
67°
59°
22
65°
59°
23
67°
58°
24
69°
58°
25
72°
57°
26
72°
55°
27
66°
53°
28
71°
58°
29
72°
59°
30
73°
59°
1
73°
58°
2
71°
55°
3
70°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Oswego
Oswego's September 2026 forecast shows daily high temperatures ranging from 65° to 78°, with overnight lows between 45° and 69°. The average high for September is 71° with an average low of 58°. 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 Oswego. See also: October | November | December.
