Planning for the weather is a good way to make your trip to Geiranger relaxing and enjoyable, especially when you’re splurging. The hottest months are usually July and August, with an average temperature of 11°C, while the coldest months are January and December, with an average of -5°C. The rainiest months in Geiranger are December, October, July and August, with each month seeing an average of 192 mm of rainfall.