Every time you check the forecast for Sunday in Green Bay, the projected temperature seems to drop. The latest from the National Weather Service:

Sunday: Partly sunny and cold, with a high near 0. Wind chill values between -20 and -25. Northwest wind 10 to 14 mph, with gusts as high as 20 mph.

Sunday Night: Mostly cloudy, with a low around -22. West northwest wind 14 to 18 mph, with gusts as high as 26 mph.

Head coach Jim Harbaugh was asked, again, about taking his team into such frigid conditions. This time, Harbaugh offered a memorable response.

“We’re aware of it, and we’ll pack all our shoe options,” he said. “The guys will put clothes on that they’ll be able to move around in, and then you start playing. The heart rate ramps up, hot blood races to the arteries, to the vessels, to the capillaries, and they’re distributed to the fingers and the toes. And an athlete the age and health of these guys, that hot blood will be racing around.”

That hot blood might not race around inside cornerback Carlos Rogers. He missed practice again today, nursing a strained hamstring, and was officially listed as questionable for Sunday’s game. Rogers, wearing sweats, walked past reporters while his teammates completed practice.

“I ran on it, but I don’t know,” he said of his hamstring.

Not exactly brimming with confidence, eh?

If Rogers cannot play Sunday, and that seems the most likely scenario, then Tramaine Brock, Tarell Brown and Eric Wright will be San Francisco’s top three cornerbacks (and the Packers often use a three-wideout formation). Wright was a limited participant in practice for the second consecutive day, dealing with his own hamstring injury. He’s also listed as questionable.

Also worth noting: Wide receiver Michael Crabtree appeared on the injury report for the first time, with a quadriceps issue. Crabtree, apparently at full strength Wednesday and Thursday, was a limited participant in today’s practice. The 49ers listed him as probable for Sunday’s game.

Other players listed as probable: WR Jon Baldwin (illness), LB Navorro Bowman (wrist), CB Tarell Brown (ribs), C Jonathan Goodwin (not injury related), RB Frank Gore (knee), G Mike Iupati (knee) and DT Justin Smith (shoulder). In addition to Rogers and Wright, linebacker Dan Skuta (foot) also was listed as questionable.