S
M
T
W
T
F
S
30
101°
74°
31
101°
76°
1
101°
74°
2
101°
78°
3
101°
76°
4
101°
74°
5
103°
74°
6
105°
72°
7
102°
73°
8
103°
77°
9
102°
78°
10
78°
66°
11
89°
65°
12
90°
70°
13
89°
67°
14
98°
72°
15
100°
77°
16
98°
74°
17
98°
75°
18
96°
74°
19
95°
75°
20
92°
71°
21
78°
63°
22
80°
58°
23
79°
56°
24
81°
60°
25
81°
65°
26
82°
64°
27
84°
63°
28
80°
57°
29
79°
55°
30
76°
54°
1
76°
54°
2
74°
52°
3
77°
59°
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 74° to 84°, with overnight lows between 52° and 65°. The average high for September is 79° 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.
