S
M
T
W
T
F
S
30
87°
67°
31
90°
68°
1
96°
72°
2
97°
73°
3
98°
73°
4
96°
70°
5
86°
64°
6
80°
61°
7
82°
60°
8
78°
60°
9
79°
63°
10
79°
65°
11
82°
62°
12
79°
60°
13
81°
59°
14
79°
57°
15
78°
61°
16
74°
61°
17
74°
57°
18
73°
53°
19
72°
52°
20
72°
53°
21
75°
54°
22
77°
55°
23
79°
59°
24
80°
58°
25
78°
57°
26
75°
57°
27
76°
58°
28
75°
57°
29
78°
56°
30
73°
54°
1
70°
51°
2
69°
52°
3
74°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Lake Monticello
Lake Monticello's September 2026 forecast shows daily high temperatures ranging from 69° to 98°, with overnight lows between 51° and 73°. The average high for September is 79° with an average low of 59°. 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 Lake Monticello. See also: October | November | December.
