Clothes that keep you dry and cut out the wind go a long way to keeping you warm.
By and large evaporative heat losses due to being wet can be far greater than straightforward conductive heat losses . Conductive heat losses are far far greater with a wind to increase the rate of conduction away from your body. Insulation is important and gortex is not a great insulating material but combined with a couple of insulating layers it will keep you far warmer than any amount of insulation and poor protection against wind and wet.
By and large evaporative heat losses due to being wet can be far greater than straightforward conductive heat losses . Conductive heat losses are far far greater with a wind to increase the rate of conduction away from your body. Insulation is important and gortex is not a great insulating material but combined with a couple of insulating layers it will keep you far warmer than any amount of insulation and poor protection against wind and wet.