S
M
T
W
T
F
S
30
75°
50°
31
78°
53°
1
80°
50°
2
74°
49°
3
75°
54°
4
80°
56°
5
81°
56°
6
80°
54°
7
75°
51°
8
74°
48°
9
77°
55°
10
78°
53°
11
75°
54°
12
76°
54°
13
78°
50°
14
72°
45°
15
70°
45°
16
71°
44°
17
71°
48°
18
74°
51°
19
77°
51°
20
78°
52°
21
70°
46°
22
75°
50°
23
70°
51°
24
77°
43°
25
69°
41°
26
68°
48°
27
Hist. Avg.
70°
44°
28
Hist. Avg.
70°
43°
29
Hist. Avg.
69°
43°
30
Hist. Avg.
69°
42°
1
Hist. Avg.
69°
42°
2
Hist. Avg.
68°
42°
3
Hist. Avg.
68°
41°
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 68° to 81°, with overnight lows between 41° and 56°. The average high for September is 75° with an average low of 50°. 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.
