For the best visibility, the night needs to be clear; whether or not there is auroral activity is irrelevant if there are clouds obscuring your view. Summer is not a great time to see them, as it is always light, so any potential activity is masked by the light. Hense, sadly this does not coincide with the best time to see polar bears, due to the midnight sun. During the winter activity by the Auroral Borealis would be clearer as the nights are dark. Although technically they could be there any time of year.