Fire at higher elevations

I frequent a camp site at 10,000 feet in the Uinta Mountains and have never had an issue, but for some reason it was a lot harder to make a fire today. It was also difficult keeping it going as well with the same two types of wood we always bring from a local store. What could cause that?

The people around us were having issues as well. Again, I'm there multiple times a year and have never had an issue before.