The California sky currently looks like something out of a science fiction novel, which is something that the NFL -- and specifically the San Francisco 49ers -- are paying close attention to as the Week 1 opener at Levi's Stadium looms. Wildfires continue to burn all through the state, and combined with the current heatwave rolling through the region, folks in the Bay Area found themselves looking up at an orange sky along with falling ash this week. 

That created an eerie setting as the 49ers hit the field for a walkthrough practice session outside of the stadium on Wednesday as they gear up for their opener against the Arizona Cardinals

"We just got back in from walkthrough and it's orange out here, too," coach Kyle Shanahan told reporters, via ESPN's Nick Wagoner. "I feel like I'm in 'The Book of Eli' -- it's like an apocalyptic state out there."

It should be noted that while it may look like the end times in Santa Clara, it is safe for the Niners to be outside practicing. Shanahan said that the air quality has not reached dangerous levels as the air quality index was a healthy 69 to start the walkthrough practice and stayed in that range throughout.

"Surprisingly, the air quality doesn't seem as bad as it looks," Shanahan said. "A few weeks ago when we had it or last week, it got up, it got past 150 here for us. But today when we were just out there 15 minutes ago, that air quality was at 69, I think, which isn't close to what it's been. It definitely looked different out there." 

In late August, the club did alter its practice schedule due to air quality concerns. The NFL will not allow teams to play or practice outside if the air quality index should reach or surpass 200, so this is something to keep a note of as Sunday's opener approaches.