This is an image of the lower portion of the east facing window in the NE bedroom located on the second floor. I have shut this currently unused room up to not waste heat and I have also not yet managed to get the windows sealed using the double-sided tape and clear shrink-wrap process. Notice the thick layer of frost on crank unit; the metal on these windows is such an efficient heat conductor that when the temperature drops below -18 F it’s not unusual to see anything of metal construction with contact to the outside air showing a layer of frost on it even with an interior temperature of 58 F. In this case the air temperature was -23 F.
Alaskan at Last! 
Wow, now that is something I’ve thought might be possible but haven’t seen before…..
Hey Cathy, its all a function of temperature; once the outdoor temp rose to -11 F the frost started to disappear rapidly and within a couple of hours was largely gone. It seems to start once the exterior temps drop into the minus teens but it also requires at least half a day of consistently cold weather to see the frost start to form. I was interested in that the internal relative humidity is right around 50% (+/- 3%) so its not really dry but also not really damp especially since the main floor of the house is around 61 F which the upstairs varies from the upper forties – in the rooms that are shut up when the exterior temps drop into the minus twenties – to the upper fifties in the master bedroom. Still waiting on some good snow; seems like we just can’t buy a foot now that the cooler temps have returned…