S
M
T
W
T
F
S
30
78°
58°
31
79°
57°
1
81°
58°
2
77°
56°
3
77°
55°
4
78°
57°
5
78°
60°
6
76°
62°
7
81°
56°
8
81°
59°
9
80°
63°
10
82°
63°
11
83°
62°
12
83°
54°
13
82°
53°
14
75°
59°
15
77°
60°
16
75°
60°
17
78°
57°
18
80°
52°
19
74°
58°
20
75°
50°
21
79°
49°
22
71°
47°
23
72°
57°
24
77°
58°
25
Hist. Avg.
74°
52°
26
Hist. Avg.
74°
51°
27
Hist. Avg.
73°
51°
28
Hist. Avg.
73°
50°
29
Hist. Avg.
72°
50°
30
Hist. Avg.
72°
49°
1
Hist. Avg.
72°
49°
2
Hist. Avg.
71°
49°
3
Hist. Avg.
71°
48°
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 71° to 83°, with overnight lows between 47° and 63°. The average high for September is 78° with an average low of 57°. 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.
