S
M
T
W
T
F
S
30
84°
64°
31
87°
66°
1
88°
67°
2
89°
67°
3
87°
68°
4
88°
68°
5
88°
63°
6
84°
64°
7
85°
67°
8
84°
65°
9
83°
66°
10
85°
66°
11
86°
65°
12
87°
66°
13
87°
66°
14
86°
67°
15
87°
66°
16
86°
65°
17
85°
65°
18
85°
64°
19
84°
61°
20
84°
59°
21
83°
63°
22
82°
63°
23
83°
62°
24
84°
57°
25
83°
56°
26
81°
60°
27
82°
61°
28
81°
58°
29
80°
59°
30
81°
60°
1
80°
59°
2
81°
59°
3
82°
60°
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 80° to 89°, with overnight lows between 56° and 68°. The average high for September is 84° with an average low of 63°. 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.
