49ers switch unis before hottest-ever game at Levi's Stadium

SANTA CLARA, Calif. -- As San Francisco 49ers players walked out of the locker room Friday afternoon, they were greeted by a table full of water bottles, energy bars and other supplements meant to bolster their hydration.

Under normal circumstances, no such table exists but the reason for this one was made clear by a black and white sign attached to it warning that Sunday's game against the Arizona Cardinals is going to be abnormally hot.

According to AccuWeather, the high for Sunday will be 99 degrees, which wouldn't be anything new if the game were in Arizona. Instead, it's projected to be the hottest game in the 11-year history of Levi's Stadium.

"We have never known in advance how hot it was going to be," coach Kyle Shanahan said. "And honestly since I've been here it never seems too hot. I feel like even on the hottest days, I still need a hoodie at some time during that day. But this week has felt different and I'm sure Sunday is going to [also]."

Indeed, if forecasts hold up, Sunday will easily surpass the previous temperature highs for games at Levi's. On Aug. 31, 2017, the Niners hosted the Los Angeles Chargers for a preseason game with a temperature of 90 degrees at kickoff. The hottest kickoff temperature for a regular-season game -- 88 degrees -- was on Oct. 3, 2021, against the Seattle Seahawks. The Niners lost that game 28-21.

With the looming heat in mind, the 49ers took multiple steps to try to help this week. First, they submitted a request to the NFL to wear their all-white uniforms. According to Shanahan, the league denied that petition, noting that the rules stipulate teams must put their home game uniform preferences in before the season starts.

"When I was on the East Coast, that was such a big deal," Shanahan said. "Being in Tampa Bay, you always wanted to wear those whites early in the year. We didn't have to worry about that much out here. ... In order for us to do it, we've kind of got to make a conscious decision or a commitment before the year that we wear all whites until the middle of October and then go to normal. But it's not usually this hot. So, we'll probably do that now just in case."

The best the 49ers can do on short notice this week is ditch their usual red jersey and gold pants combo for their red throwback jerseys and white pants, something Shanahan said, "hopefully helps a little."

Shanahan and the training staff have been pushing the importance of hydration all week. Temperatures hovered in the mid to high 90s for 49ers practices Wednesday and Thursday and reached the upper 80s Friday, which has helped a bit with acclimation.

Shanahan said many players already take IVs as part of their weekly routine but he expects that to increase on Sunday. Left tackle Trent Williams has taken IVs twice this season in games where heat wasn't as prevalent but he doesn't seem too concerned about it since he spends most of his offseasons in the Houston area.

"No comparison at all," Williams said. "It's nothing. ... It all depends on where your hydration level is."

Of course, there may not be an opponent better suited to playing in the heat than the Cardinals. Arizona regularly practices in triple digit temperatures and did again this week.

"I learned this a long time ago," Cardinals coach Jonathan Gannon said. "The advantage is to the team that thinks it's an advantage. We're adapted to it."

For the Niners, attrition might be an even bigger challenge than the heat. They ruled out two players (defensive lineman Yetur Gross-Matos, linebacker Demetrius Flannigan-Fowles), declared receiver Chris Conley doubtful and have five more players, including linebacker Fred Warner (ankle) and tight end George Kittle (ribs) listed as questionable.

Warner and Kittle both expressed optimism this week that they'll play against the Cardinals and participated in Friday's practice. The heat, paired with turning around and playing Thursday at theSeattle Seahawks, only makes for more of a challenge.

"We've got two games here in the next [six] days," Shanahan said. "When things get close to Sunday, you always think about that stuff, but usually if they're all right to play that Sunday, you rarely say, 'Hey, no, let's not do it this Sunday. Let's wait till the next one.' And if they're not all right to play, then they're usually not all right to play the next one either."

ESPN's Josh Weinfuss contributed to this report.