climate and the seasons

The Void exists at both the north and south pole of Scarterra. The Barrier keeps the Void from devouring all life on Scarterra, but it does not keep the Void out entirely. The Void passively acts as a heat sink. The closer one gets to the poles, the colder the climate. This is because the Void is sucking out Scarterra's heat.

The Barrier against the Void needs constant shoring up. The Barrier weakens every year near the anniversary of The Divine Rebellion every year which happens to occur around the Winter Seasonal Stellar Day . The Barrier is strongest about six months away from the anniversary on the Summer Stellar Day.
Thus the Void indirectly causes the seasons every year.