In Northern Idaho, it sure seems to be in the late fall, around Octoberish, but the truth is, it happens whenever the sun belches radiation, so it happens whenever. I just tend to think that the best time for seeing it, when it's most likely to be seen, is late fall. Alaska could be different though.
Best time to see them is in late fall and all winter. Mainly because it's darker then. Really hard to see them during the sumner when it never really gets dark.
They happen year 'round though.
As for where...any place where you've got little to no light pollution.
Beautiful collection, I very seldom have a camera . But have many good memories of late night sights such as those shown. Alaska is a great place to live.