S
M
T
W
T
F
S
30
82°
62°
31
86°
63°
1
87°
64°
2
87°
64°
3
86°
63°
4
85°
57°
5
81°
62°
6
86°
64°
7
86°
63°
8
85°
63°
9
81°
62°
10
82°
63°
11
85°
62°
12
86°
62°
13
84°
61°
14
85°
62°
15
85°
62°
16
84°
61°
17
84°
55°
18
82°
54°
19
77°
53°
20
77°
52°
21
75°
52°
22
75°
53°
23
77°
54°
24
81°
53°
25
80°
57°
26
81°
57°
27
80°
56°
28
79°
55°
29
78°
54°
30
79°
54°
1
76°
52°
2
79°
53°
3
73°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Monticello
Monticello's September 2026 forecast shows daily high temperatures ranging from 73° to 87°, with overnight lows between 50° and 64°. The average high for September is 82° 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 Monticello. See also: October | November | December.
