BMW Repair: overheating question, bmw 330xi, antifreeze

Question
I have a BMW 330xi, 2001 w/ about 106K miles.  The radiator light just came on and then the heat gauge went way into the red after driving just a few miles.  Any ideas what this is.  I live in WI and the temp has been way below freezing lately.

Answer
(I'm in MN, and understand your cold!)

First, are you sure it has adequate antifreeze? If it does, and you have an adequate amount of coolant, then it's likely a stuck thermostat.

BEWARE!  These BMW's HATE to be overheated.  They are very prone to headgasket damage if run hot.