You can make your room as hot or as cold as you would like it. The thermostat goes from 40 to 90. If you set it to 40 it will probably be colder than that since it can be drafty in high winds as the building is not 100% wind proof. The living quarters are set to around 65 to 70, but that too can be adjusted after asking the three other crew members that are up this week. So in general, pack layers and then peel off what you don't need until you reach a warm equilibrium. We have had some wear shorts while cooking as the kitchen can still get warm. But have warm clothes ready in case of sudden emergency that forces evacuation.
Staff Meteorologist/Night Observer, KMWN (Mt Washington Obs., NH)