S
M
T
W
T
F
S
30
85°
59°
31
76°
70°
1
90°
72°
2
73°
69°
3
89°
76°
4
88°
74°
5
81°
66°
6
76°
62°
7
82°
59°
8
78°
67°
9
85°
73°
10
85°
67°
11
80°
64°
12
76°
68°
13
81°
67°
14
82°
65°
15
80°
67°
16
79°
61°
17
77°
61°
18
74°
57°
19
74°
55°
20
72°
58°
21
73°
57°
22
70°
61°
23
70°
60°
24
71°
60°
25
72°
58°
26
75°
58°
27
71°
55°
28
71°
58°
29
75°
59°
30
76°
59°
1
75°
58°
2
74°
59°
3
73°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Interlaken
Interlaken's September 2026 forecast shows daily high temperatures ranging from 70° to 85°, with overnight lows between 55° and 73°. The average high for September is 76° with an average low of 61°. 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 Interlaken. See also: October | November | December.
