The average temperature in September is only 0.3 ˚C so it is important to bring clothing that will keep you warm.
Woolen layers, mittens, hat, a good jacket and warm pants are required if you are planning to be outdoors. If you are going on the boat trip you should bring extra warm clothing - it can get quite cold on deck. You will also need proper shoes, like mountain boots.

Overall dresscode: Arctic casual, meaning leave your suit back home
Tenant meeting, Wed 7: Casual
Hosted tenant dinner, Wed 7: Business Casual

Most places in Svalbard have kept the old mining company town tradition of not to use outdoor shoes indoors. You will for instant be asked to take off your shoes at the hotel etc. For your comfort, we advise you to bring indoor shoes or slippers.