It's going to be freezing for Sunday's 49ers-Packers NFC wild-card playoff game in Green Bay Sunday. Temperatures are projected to be between 4 and 8 degrees for the 1:40 p.m. (PST) kickoff. And, no doubt, the weather will play some role in the game.But 49ers head coach Jim Harbaugh doesn't want to hear about it.Harbaugh, who as a college player at Michigan and an NFL quarterback in Chicago and Indianapolis has experienced cold and snow, is tired of hearing about how cold it's going to be, and what kind of impact the weather might have on his warm-weather team from California.When it was suggested this week that the Niners might have some difficulty playing well this Sunday, Harbaugh dismissed the notion, noted the San Francisco Chronicle's Eric Branch."Is it?" said Harbaugh. "I mean, do you have some study on that?"And, no doubt, the 49ers' third-year head coach is right. Cold hands, rock-hard footballs or freezing winds may cause some mistakes Sunday, but the playoff matchup will more likely be determined by these five factors:1 – The Packers run defense: If Green Bay can stop the 49ers from running the ball, it would be the single most important thing the Packers can do...