Colonel Sun

Someone on Facebook told me that in Tromso, which is the northernmost point of the trip, the nights are still bright in mid August, so there's no chance for the lights. However, what he said, you can see the lights in mid August more in the south where the nights are already dark. The ship will be sailing from Tromso back to Amsterdam between Aug 12 and 22, so maybe there will be a chance to see the lights somewhere along the way?
Anyone took that cruise in the past?

What specific Northern European cruise would you recommend for this purpose?
Doesn't have to be limited to RCI.

We are considering an Arctic Circle cruise starting Aug 10 from Amsterdam. It's 12 days and one of the of primary reasons is watching northern lights.
Question: are northern lights visible from Northern Norway in mid August. We really don't want to book for this sole purpose and find out it's too early in the year.

Thank you