S
M
T
W
T
F
S
30
77°
34°
31
75°
37°
1
61°
39°
2
65°
40°
3
66°
42°
4
63°
38°
5
68°
38°
6
69°
39°
7
68°
38°
8
70°
44°
9
72°
46°
10
68°
40°
11
70°
41°
12
70°
41°
13
69°
42°
14
68°
40°
15
72°
40°
16
75°
45°
17
74°
44°
18
65°
40°
19
65°
38°
20
68°
39°
21
72°
42°
22
72°
42°
23
71°
41°
24
67°
39°
25
66°
39°
26
69°
38°
27
71°
41°
28
70°
41°
29
70°
40°
30
69°
39°
1
70°
40°
2
70°
39°
3
68°
38°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mammoth Lakes
Mammoth Lakes's September 2026 forecast shows daily high temperatures ranging from 61° to 75°, with overnight lows between 38° and 46°. The average high for September is 69° with an average low of 40°. 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 Mammoth Lakes. See also: October | November | December.
