S
M
T
W
T
F
S
30
78°
56°
31
78°
55°
1
77°
54°
2
76°
51°
3
74°
51°
4
72°
53°
5
69°
45°
6
67°
53°
7
67°
53°
8
73°
52°
9
75°
54°
10
66°
48°
11
64°
50°
12
66°
50°
13
70°
54°
14
74°
53°
15
75°
48°
16
65°
45°
17
64°
49°
18
69°
48°
19
64°
46°
20
65°
45°
21
Hist. Avg.
67°
48°
22
Hist. Avg.
67°
48°
23
Hist. Avg.
67°
47°
24
Hist. Avg.
66°
47°
25
Hist. Avg.
66°
47°
26
Hist. Avg.
66°
47°
27
Hist. Avg.
66°
47°
28
Hist. Avg.
65°
46°
29
Hist. Avg.
65°
46°
30
Hist. Avg.
65°
46°
1
Hist. Avg.
64°
46°
2
Hist. Avg.
64°
46°
3
Hist. Avg.
64°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Mount Vernon
Mount Vernon's September 2026 forecast shows daily high temperatures ranging from 64° to 78°, with overnight lows between 45° and 56°. The average high for September is 70° with an average low of 51°. 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 Mount Vernon. See also: October | November | December.
