Seasonal Stellar Days

Scarterra does not have an axial tilt like real world Earth. Every day is 12 hours and ever night is 12 hours. Variation in the seasons is entirely because the strength of the The Barrier waxes and wanes on a predictable cycle.
Four particularly bright stars slowly revolve around each other in the night sky. Each star corresponds with a particular season. When the Spring star is higher than the others, it is officially spring. When the Autumn star is higher than the others, it is officially autumn, and so on and so forth.
Spring Stellar Day 
Summer Stellar Day
The Autumn Stellar Day 
Winter Stellar Day 
The four stellar days mark the days where one of the four season stars overtakes the other three and begins a 90-day or 95 day cycle of ascendancy. (winter is 5 days longer than the other seasons).
The midway points between the stellar days are known as the Tween Days and are times of metaphysical and cultural significance.
On the Winter Stellar Day, the Barrier is relatively weak allowing The Void to siphon off a lot of heat away from Scarterra. On the Summer Stellar Day the Barrier is relatively strong allowing the Void to siphon comparatively little heat away from Scarterra.

Type

Metaphysical, Astral