S
M
T
W
T
F
S
30
77°
62°
31
71°
62°
1
76°
55°
2
74°
48°
3
77°
51°
4
76°
54°
5
64°
51°
6
59°
46°
7
60°
43°
8
71°
41°
9
69°
55°
10
N/A
11
74°
59°
12
67°
51°
13
57°
50°
14
58°
51°
15
71°
41°
16
70°
48°
17
68°
52°
18
72°
55°
19
71°
56°
20
78°
57°
21
80°
55°
22
81°
61°
23
72°
59°
24
67°
58°
25
74°
58°
26
75°
59°
27
74°
59°
28
74°
58°
29
73°
59°
30
75°
59°
1
73°
58°
2
68°
59°
3
69°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Monte Castelo
Monte Castelo's September 2026 forecast shows daily high temperatures ranging from 57° to 81°, with overnight lows between 41° and 61°. The average high for September is 71° with an average low of 56°. 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 Monte Castelo. See also: October | November | December.