Why are the 49ers wearing white jerseys at home vs. the Cardinals?

The San Francisco 49ers will take the field in their white throwback jerseys on Sunday when they host the Arizona Cardinals. Interestingly, the team will also wear lighter uniforms in both of their first two home games this season, suiting up in their white primary jerseys again in Week 4 against the Jacksonville Jaguars.

The reason is simple: to beat the September heat in Santa Clara.

"I unfortunately had to decide that back in April this year because last year, we had a heat wave when we played them (the Cardinals)," head coach Kyle Shanahan explained during a recent radio interview.

Shanahan, who began his NFL coaching career as an assistant with the Tampa Bay Buccaneers, said he learned early on the value of wearing lighter-colored jerseys in hot weather—especially when it forces the visiting team to wear darker uniforms.

"I thought it was a huge advantage for us," Shanahan said. "I can always feel that disadvantage when you go to places like Miami and stuff. Never thought about it out here. I never thought it got too hot, but it was that one day, and we knew it was going to be. So, we asked the NFL if we could wear our whites [last year], and they said you had to decide on that before the season started."

The game Shanahan referenced was the 49ers' 24-23 Week 5 loss to the Cardinals last season, which kicked off in 89-degree heat at Levi's Stadium.

"And so, I did think that could have been an advantage that we weren't able to take advantage of," Shanahan continued. "So I had to decide in April, and I tried to look at the weather, and they didn't have it yet [laughs]. So I just went with the percentages. Well, hey, it might be hot, so we'll do white for the first two home games."

Shanahan added that while the NFL allows for last-minute uniform changes if both teams agree, no opponent is likely to forfeit the advantage of seeing the home team sweat it out in darker jerseys.

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