Prepare yourself for some wind and an average summer temperature of around 5°C.
Even if we do have warmer days in Svalbard, it is always better to have warm clothes. A proper local always wear wool thermals closest to the body in one or two layers. In summertime a thick sweater or fleece jacket might be enough as a mid-layer, but make sure you top it all up with a wind- and waterproof layer on top. If you tend to get cold it is smart to bring along a light down or primaloft jacket as well. At last, steady shoes that can get dirty, woollen socks, gloves, buff, hat and sunglasses.
In Svalbard each participant is responsible to dress properly for the adventure. This is for your wellbeing and safety when it comes to hypothermia, frostbite and or other injuries that can occur due to lack of clothing or shoes. Kindly as us for advice if you are in doubt.