Where do you wish to view the bears?
What kind of bear do you wish to see? Polar, Black or Brown (Grizzley)?
In Southeast Alaska, you'll be most apt to see bears when the Salmon are coming into the streams to spawn because the bears feed on them. That usually occurs during August-September. I don't know what to tell you about other areas.
There are expensive tours (flight seeing) that take you to bear viewing sites -- but again--seeing a bear usually depends on the salmon runs. No one will guarantee that you will see a bear on their tour.
