Hard maple isn't as bad as yellow birch, but 4 or 5 weeks it's gonna check on the ends. I've seen hard maple turn black on the ends after 4 weeks (stovewood), especially pieces in the direct sun. But, I don't think the stain will travel until after the bugs get chewing and making galleries. Yellow birch will get blue-green stain in the sapwood after 3 weeks in the hot sun. In the winter months , in freezing cold climate, you won't get stain, accept maybe the ends at the end of April.