[parlasl]

Cockatiels will be comfortable in the temperatures you are comfortable in (so long as you don't live in arctic temperatures!). They're pretty adaptable. Mine live outside, and don't mind the cold of winter (because it comes on slowly) and the horrid heat of our summer.

About leaving them alone... yes, they can be, but you need to make sure they have plenty of toys to keep them amused! Even swapping toys around regularly, to give them some variation. Then you need to make sure you give them loads of TLC when you get home, and if they're tame that they get out and have a good play and wander.