If you prefer to explore when it's quieter, head here in April. You could snag some great deals on hotels with parking in Birkenes around then. The warmest weather is in July, with temperatures ranging from 55ºF (13ºC) to 66ºF (19ºC). It's generally coolest in February, averaging between 28ºF (-2ºC) and 34ºF (1ºC).