S
M
T
W
T
F
S
30
86°
57°
31
89°
59°
1
90°
59°
2
90°
58°
3
86°
58°
4
84°
59°
5
88°
59°
6
90°
58°
7
90°
58°
8
89°
59°
9
89°
55°
10
85°
51°
11
83°
51°
12
84°
52°
13
83°
55°
14
82°
54°
15
85°
52°
16
87°
55°
17
86°
59°
18
88°
59°
19
80°
58°
20
81°
58°
21
87°
57°
22
88°
58°
23
85°
58°
24
85°
57°
25
87°
57°
26
86°
56°
27
86°
56°
28
81°
55°
29
80°
57°
30
81°
56°
1
86°
57°
2
87°
56°
3
86°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Altamont
Altamont's September 2026 forecast shows daily high temperatures ranging from 80° to 90°, with overnight lows between 51° and 59°. The average high for September is 86° 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 Altamont. See also: October | November | December.