S
M
T
W
T
F
S
30
87°
62°
31
84°
58°
1
81°
58°
2
80°
59°
3
81°
59°
4
81°
60°
5
85°
64°
6
80°
66°
7
86°
63°
8
83°
57°
9
79°
57°
10
78°
56°
11
79°
55°
12
78°
57°
13
76°
56°
14
76°
55°
15
77°
56°
16
78°
58°
17
77°
55°
18
78°
59°
19
81°
61°
20
78°
57°
21
74°
51°
22
73°
51°
23
Hist. Avg.
78°
56°
24
Hist. Avg.
77°
55°
25
Hist. Avg.
77°
55°
26
Hist. Avg.
77°
54°
27
Hist. Avg.
76°
54°
28
Hist. Avg.
76°
54°
29
Hist. Avg.
76°
53°
30
Hist. Avg.
75°
53°
1
Hist. Avg.
75°
53°
2
Hist. Avg.
74°
52°
3
Hist. Avg.
74°
52°
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 73° to 87°, with overnight lows between 51° and 66°. The average high for September is 80° 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 Mount Vernon. See also: October | November | December.
