you can start here on the general forum:
normally when you see a season is ending, it is a prelude to a major patch that is coming soon after. When a season ends, it is followed by another season (patch) be it major or mini.
Severs always will be down for extended periods leading up to “the end” of the season because they are trying to push data, downloads, and other information so when the patch or exp launches we have little to no problems the day it goes live.
Also all the links I posted will give you more information or, just read/watch the forums as you will find like 15 angry post about what is going on.