Why does static elecctricity only happen in winter?

In the winter more static electricity builds up in our homes and because we turn on our heaters and it sucks the moisture out of the air. In summer months water in the air can help get rid of or dissipate the electrons that we pick up when we move around. But When it’s drier the charge will collect and cling on to us. Then it builds up and then we get shocked and so forth.