I can assure you it gets cold where I am. Have had a drain stick open due to cold before.
We have (or used to I'd have to check) the option to defer it to main base, not sure we do on the airbuses anymore, will check. Adding warm fuel is ok provided you have sufficient time to allow it to settle, unfortunately on the line (where me is) we don't have that luxury.
So the answer is many and varied and depends on your airline and how good your planners are at getting it on the ground somewhere warm if it's due a weekly!