S
M
T
W
T
F
S
30
83°
64°
31
86°
65°
1
88°
61°
2
83°
59°
3
81°
59°
4
81°
58°
5
82°
58°
6
83°
59°
7
84°
58°
8
85°
63°
9
85°
63°
10
86°
62°
11
86°
62°
12
85°
63°
13
86°
63°
14
85°
62°
15
86°
62°
16
86°
60°
17
83°
61°
18
83°
61°
19
84°
60°
20
82°
60°
21
83°
59°
22
83°
53°
23
78°
55°
24
76°
58°
25
Hist. Avg.
78°
58°
26
Hist. Avg.
78°
58°
27
Hist. Avg.
78°
58°
28
Hist. Avg.
77°
57°
29
Hist. Avg.
77°
57°
30
Hist. Avg.
77°
56°
1
Hist. Avg.
76°
56°
2
Hist. Avg.
76°
56°
3
Hist. Avg.
76°
55°
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 76° to 88°, with overnight lows between 53° and 65°. The average high for September is 84° with an average low of 60°. 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.
