September Weather in Interlaken, United States

Last updated: June 24, 2025

In September, the average temperature in Interlaken, United States hovers around 18°C (65°F), offering pleasant weather for exploration. However, be prepared for a range: temperatures can dip to a minimum of 8°C (47°F) and soar to a maximum of 37°C (98°F). With a mere 2 mm (0.1 in) of precipitation over 0 days, the chances of rain are low, allowing you to enjoy the outdoors. Finally, the average humidity stands at 55%, contributing to the comfortable atmosphere of this charming destination.

September Temperature in Interlaken

In September in Interlaken, the average temperature is 18°C (65°F), with maximums reaching up to 37°C (98°F) and minimums dropping as low as 8°C (47°F). This range makes it a great time to visit, as you can enjoy warm days while still having cooler evenings to relax.

September Weather in Interlaken: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Interlaken, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Interlaken, September typically has an average temperature of 18°C (65°F), with highs reaching up to 37°C (98°F) and lows dropping to around 8°C (47°F).

Data source: Temperature data for Interlaken generated using information from the Copernicus Climate Change Service.

September Precipitation in Interlaken

In Interlaken in September, the precipitation amount is 2 mm (0.1 in) during a span of 0 days.

September Precipitation Trends in Interlaken

The chart displays monthly precipitation patterns in Interlaken, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Interlaken, September typically receives around 2 mm (0.1 inches) of precipitation spread over approximately 0 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Interlaken

In Interlaken in September humidity is 55%. With an average temperature of 18°C (65°F), this humidity feels like a gentle embrace, creating a comfortable yet slightly sticky atmosphere that is perfect for leisurely strolls and outdoor adventures.

September Average Humidity in Interlaken

This chart illustrates the average monthly humidity levels in Interlaken, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Interlaken is approximately 55%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Interlaken

In Interlaken in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Interlaken.

Maximum UV Index Levels in Interlaken for September

The chart shows the monthly maximum UV Index (UVI) for Interlaken in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Interlaken typically reaches 9, which falls under the very high exposure category.

Data source: Interlaken September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How September Weather in Interlaken Compares to Other Months

Weather in Interlaken varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Interlaken, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Interlaken, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	11°C (51°F)	122 mm (4.8 inches)	82%	moderate
February Weather	11°C (52°F)	105 mm (4.1 inches)	84%	moderate
March Weather	12°C (54°F)	88 mm (3.5 inches)	82%	very high
April Weather	13°C (57°F)	32 mm (1.2 inches)	78%	very high
May Weather	15°C (59°F)	19 mm (0.7 inches)	71%	extreme
June Weather	17°C (62°F)	1 mm (0.1 inches)	64%	extreme
July Weather	17°C (63°F)	1 mm (0.0 inches)	58%	extreme
August Weather	18°C (65°F)	1 mm (0.0 inches)	54%	very high
September Weather	18°C (65°F)	2 mm (0.1 inches)	55%	very high
October Weather	16°C (62°F)	22 mm (0.9 inches)	62%	high
November Weather	13°C (56°F)	42 mm (1.7 inches)	78%	moderate
December Weather	10°C (51°F)	92 mm (3.6 inches)	80%	moderate