S
M
T
W
T
F
S
30
93°
66°
31
92°
68°
1
93°
69°
2
93°
70°
3
92°
69°
4
93°
69°
5
92°
68°
6
85°
68°
7
85°
66°
8
87°
64°
9
87°
62°
10
86°
61°
11
84°
62°
12
85°
61°
13
85°
60°
14
84°
61°
15
84°
60°
16
83°
62°
17
84°
61°
18
85°
60°
19
83°
61°
20
84°
62°
21
86°
65°
22
87°
65°
23
85°
66°
24
90°
66°
25
91°
65°
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 83° to 93°, with overnight lows between 60° and 70°. 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.
