When does that sun set?

We were told about a back road leading up to a fire lookout and headed up there late in the evening. We talked to the fellow who lives there with his wife during fire season. He climbs the lookout tower every morning at 9:00 and stays there all day searching the horizon. Fire is a constant threat in the Yukon. We’ve passed miles of sites of former forest fires the whole way up. 
We are aware of the later setting sun. It is strangely daylight long after it should be! Sun is setting around 12:45 am these days.