S
M
T
W
T
F
S
30
92°
68°
31
91°
68°
1
88°
67°
2
90°
66°
3
92°
66°
4
91°
67°
5
92°
67°
6
93°
68°
7
92°
68°
8
90°
67°
9
86°
67°
10
88°
66°
11
88°
67°
12
90°
68°
13
89°
67°
14
92°
68°
15
91°
67°
16
90°
65°
17
89°
64°
18
87°
67°
19
87°
66°
20
Hist. Avg.
89°
61°
21
Hist. Avg.
89°
61°
22
Hist. Avg.
89°
61°
23
Hist. Avg.
88°
61°
24
Hist. Avg.
88°
60°
25
Hist. Avg.
88°
60°
26
Hist. Avg.
88°
60°
27
Hist. Avg.
87°
60°
28
Hist. Avg.
87°
60°
29
Hist. Avg.
87°
59°
30
Hist. Avg.
87°
59°
1
Hist. Avg.
86°
59°
2
Hist. Avg.
86°
59°
3
Hist. Avg.
86°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Altadena
Altadena's September 2026 forecast shows daily high temperatures ranging from 86° to 93°, with overnight lows between 64° and 68°. The average high for September is 90° with an average low of 67°. 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.
