The winter upgrades are now LIVE in Ultimate Team. There are 70 Upgrades in total, and the full list can be found here
EA have changed the way upgrades work this year.
Upgrades apply to new players found in packs from this point forward. Existing non-IF players in your Club will not receive an upgrade.
If an upgraded player already has one or more in-forms, all of his IFs will be upgraded respectively.
If you already own the IF version of an upgraded player, your IF will be upgraded.
However, if an upgraded player with a previous IF gets upgraded across Quality tiers (eg. Bronze to Silver), his IF will not be upgraded. Ex: Januzaj has been upgraded to a Silver, but his Bronze IF will stay Bronze. This preserves the value of the IF and ensures your Bro/Sil squads aren’t negatively affected.
Notable upgrades:
This is just the first batch, you can expect more upgrades towards the end of this month.