S
M
T
W
T
F
S
30
103°
73°
31
102°
72°
1
102°
73°
2
102°
76°
3
100°
74°
4
100°
73°
5
104°
72°
6
104°
71°
7
102°
74°
8
102°
78°
9
99°
72°
10
85°
67°
11
90°
71°
12
90°
72°
13
92°
73°
14
94°
70°
15
81°
60°
16
79°
59°
17
80°
59°
18
77°
54°
19
73°
56°
20
75°
54°
21
81°
68°
22
85°
65°
23
86°
64°
24
86°
65°
25
83°
64°
26
80°
63°
27
81°
63°
28
83°
64°
29
82°
63°
30
79°
56°
1
71°
50°
2
69°
49°
3
69°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Frontenac
Frontenac's September 2026 forecast shows daily high temperatures ranging from 69° to 102°, with overnight lows between 48° and 78°. The average high for September is 83° 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 Frontenac. See also: October | November | December.
