To see if your attic is too warm, disposing you to ice damming problems, place a remote-read thermometer up in the attic space of your house. When the outside, or ambient temperatures are very cold, your attic temperature should be no more than five degrees or so warmer than the outside air. If it is, you are at risk for ice damming.
Ice damming is a fairly complex phenomena, and many different variables can play a part in the formation of large ice dams. The most common cause of ice dam formation is too much heat escaping from the building into the attic, causing it to over heat and melt the snow on the roof from the underside. Once the snow has liquefied, it trickles down to the eaves, where it re-freezes and turns to ice. When this process repeats itself over the course of several days, the ice formations can become quite large. However, attic heat is not the only variable that may contribute to ice damming, as the orientation of the rooflines, and solar exposure can have an effect. Vaulted or cathedral ceilings (as opposed to a traditional truss-framed roof with an attic) are more likely to form ice dams.