it sounds like it is the strain, but weather preventing a full finish can also lead to a lack of density. easiest way to fix that is to do light deprivation rather than trying to change the weather.
light deprivation can be as easy as putting some stakes around your plant, throwing a piece of black plastic over the stakes, and putting some rocks on the plastic edges to keep it from blowing away. use natural darkness and a few hours of light deprivation to trigger earlier flowering and earlier finishing before the cold, wet weather hits.
i have certain strains that finish denser than others.