S
M
T
W
T
F
S
30
87°
71°
31
88°
65°
1
87°
67°
2
88°
69°
3
88°
67°
4
87°
65°
5
89°
66°
6
87°
62°
7
84°
63°
8
82°
62°
9
79°
58°
10
75°
52°
11
77°
58°
12
77°
58°
13
78°
57°
14
76°
56°
15
77°
52°
16
68°
52°
17
75°
55°
18
77°
56°
19
78°
56°
20
78°
57°
21
77°
56°
22
78°
53°
23
70°
47°
24
65°
48°
25
69°
52°
26
67°
51°
27
75°
53°
28
75°
53°
29
73°
52°
30
73°
52°
1
72°
51°
2
69°
50°
3
68°
49°
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 65° to 89°, with overnight lows between 47° and 71°. The average high for September is 78° with an average low of 57°. 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.
