S
M
T
W
T
F
S
30
90°
66°
31
87°
63°
1
86°
61°
2
86°
60°
3
85°
59°
4
84°
59°
5
85°
60°
6
85°
63°
7
87°
64°
8
89°
62°
9
84°
64°
10
87°
65°
11
89°
65°
12
90°
64°
13
89°
64°
14
89°
63°
15
90°
63°
16
88°
64°
17
89°
63°
18
88°
61°
19
82°
62°
20
86°
61°
21
87°
54°
22
81°
53°
23
Hist. Avg.
82°
62°
24
Hist. Avg.
81°
61°
25
Hist. Avg.
81°
61°
26
Hist. Avg.
81°
60°
27
Hist. Avg.
80°
60°
28
Hist. Avg.
80°
60°
29
Hist. Avg.
80°
59°
30
Hist. Avg.
79°
59°
1
Hist. Avg.
79°
58°
2
Hist. Avg.
78°
58°
3
Hist. Avg.
78°
58°
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 81° to 90°, with overnight lows between 53° and 66°. The average high for September is 87° with an average low of 62°. 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.
