Casey and Clay Matthews grew up in Northridge, Calif., a Los Angeles neighborhood where the average high temperature in the month of November is 75 degrees.
This Sunday, the high in Green Bay, Wisc. is expected to be 30 degrees, with a chance of snow.
The weather isn't going to be the only thing different about Sunday's matchup between the linebacker brothers.
In the Green Bay Packers' Sunday night victory over the Chicago Bears, Clay switched from outside linebacker to inside linebacker to help with the Packers' struggling run defense. The switch worked, which means the Pro Bowl 'backer, who played the vast majority of his career snaps at outside linebacker, may line up there again this Sunday.
So he might take a few tips from Casey, his little brother more than two and a half years his junior, who is starting at inside linebacker for the Eagles this season following the season-ending injury to DeMeco Ryans.
Casey said on Wednesday that the brothers, who normally talk once or twice each week, chatted about the unexpected position switch after the game.
"Going from outside backer, always going after the quarterback and playing stacked and taking on linemen and having to tackle running backs, it was a little different," Casey said following Wednesday's training session.
Casey said their weekly chats are typically casual, catching up, seeing how the other is doing. The two don't typically talk about football, but this week he had to ask his older brother about the new wrinkle in his game. Casey said when he turned on his television Sunday night, he saw his brother at inside linebacker and assumed it was just the package Green Bay's defense was in for that play.
After watching a few series, he noticed that Clay was consistently lining up at inside linebacker. Casey said he found it funny at first, but then Clay started making plays.
"He had a pretty good game," Casey admitted with a small smile. He had to give his brother credit where it was due.
This weekend, the two brothers will face off for the first game where they're both seeing significant playing time. Last season in Green Bay, Clay was coming off a thumb injury and had a cast wrapped around his hand, hindering him from being his normal effective self. Casey was largely a special teams player, still a season away from becoming a regular on defense.
Clay is having a solid season. He's on pace to finish the season with 6.5 sacks, which would be his second-lowest total in his six years in the league and the lowest since his six sacks in 2011.
His younger brother, meanwhile, is having the best season of his young career. Casey's four starts this season are already a single-season high. He recorded his first career forced fumble in Monday night's win over the Panthers, and he's on pace to finish the year with a career-high 43 tackles.
Casey said in the locker room Wednesday that he and Clay are doing their best to avoid making a big deal out of the impending matchup, even when they know they'll field questions about it all week long.
"We try not to treat the situation any bigger than it is," Casey said. "We just need to treat it like any other game week."
Come Sunday, it's all about winning with his team, Casey said. He and Clay can talk about all the other stuff later.