How does Wraeclastians Measure Seasons?

I'm here again asking for random lore :D

We know seasons in Wraeclast match ours, as there's a "Winter" or the World, they should already have a concept of what a "winter" is. Also, the unique Platinum Valdo's Rest Watchstone "Restless Cycles", wich I think refers to the Atlas seasons say

"

"There were seasons in this strange new place, but not of sun and snow."

So that also means people from the "normal" world knows seasons as we do.

So... My questions:

When do the first season start? And how long each last?



As Wraeclast has 13 months of 28 days; does Summer (assuming is the first one) starts on "Verusi 1"? Does every season last 91 days or are they not equall in duration?


FAQ:

Q: Why?
A: I'm doing a D&D campain based on PoE's World

Unrelated but I would like a day/night cycle in PoE1 that changes the lighting and in-game music..