Verdict: Good month
Interlaken Weather in September
September hits the sweet spot in Interlaken — highs around 21°C (70°F), ideal for a full day on foot. It's also the wet side of the calendar: rain falls on about 15 days, so build flexibility into plans. Overall, September is a solid month to visit Interlaken.
Average high
21°C / 70°F
Average low
14°C / 57°F
Rain days
~15
Precipitation
144 mm
What to pack for Interlaken in September
- Layers — t-shirts under a light jacket or sweater
- Rain gear is non-negotiable — expect rain on roughly 15 days
- Comfortable walking shoes — every guide on this site assumes you'll use them
September against the rest of the year
Warmest in Interlaken: Aug (25°C / 77°F) · Coolest: Jan (7°C / 45°F) · Wettest: May (~20 rain days)
7°
2°
Jan
10°
3°
Feb
12°
3°
Mar
14°
5°
Apr
18°
9°
May
23°
14°
Jun
24°
16°
Jul
25°
16°
Aug
21°
14°
Sep
18°
10°
Oct
11°
6°
Nov
8°
2°
Dec
Daily highs / lows in °C · bars show rain days per month · ERA5 climate normals (2020–2024)