S
M
T
W
T
F
S
30
91°
67°
31
87°
63°
1
84°
60°
2
84°
60°
3
84°
60°
4
83°
65°
5
87°
69°
6
91°
72°
7
94°
71°
8
92°
67°
9
92°
71°
10
93°
69°
11
89°
69°
12
91°
68°
13
88°
67°
14
89°
64°
15
92°
68°
16
91°
68°
17
91°
67°
18
88°
64°
19
84°
62°
20
85°
63°
21
88°
64°
22
89°
65°
23
88°
65°
24
85°
62°
25
81°
58°
26
80°
59°
27
79°
57°
28
80°
58°
29
82°
60°
30
82°
61°
1
81°
59°
2
84°
61°
3
87°
64°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Altadena
Altadena's September 2026 forecast shows daily high temperatures ranging from 79° to 94°, with overnight lows between 57° and 72°. The average high for September is 87° with an average low of 64°. 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 Altadena. See also: October | November | December.
