Dress tends towards smart-casual in Norway. People are expected to be neat, tidy and well-groomed.
However, much less emphasis is placed upon what people wear than on how professional and efficient they are. Do not dress in an overtly ostentatious way or wear too much flashy, expensive jewellery as this would be contrary to just about every Jante Law. As with the men, ladies tend towards smart casual with trousers much in evidence - especially in the colder months.
If travelling in winter be sure to be appropriately and warmly dressed. It is best to wear a number of layers as, whilst cold outside, offices can be very warm indeed. Always take a good pair of gloves and a hat in the winter.