S
M
T
W
T
F
S
30
84°
64°
31
88°
59°
1
85°
55°
2
86°
63°
3
86°
34°
4
84°
34°
5
84°
36°
6
79°
34°
7
82°
34°
8
N/A
9
77°
50°
10
80°
61°
11
83°
55°
12
72°
50°
13
65°
56°
14
70°
48°
15
66°
49°
16
70°
53°
17
67°
49°
18
66°
50°
19
69°
48°
20
70°
49°
21
69°
48°
22
71°
54°
23
72°
54°
24
73°
53°
25
68°
52°
26
69°
53°
27
71°
54°
28
71°
53°
29
68°
51°
30
66°
50°
1
59°
45°
2
57°
40°
3
56°
39°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Monticello
Monticello's September 2026 forecast shows daily high temperatures ranging from 56° to 83°, with overnight lows between 39° and 61°. The average high for September is 69° with an average low of 51°. 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.
