Planning for the weather is a good way to make your trip to Brunnen relaxing and enjoyable, especially when you’re splurging. The hottest months are usually July and August, with an average temperature of 15°C, while the coldest months are January and February, with an average of 0°C. The rainiest months in Brunnen are August, July, June and May, with each month seeing an average of 230 mm of rainfall.