I recall in Anchorage a few days close to -40 degF in the 60s & 70s.  Do you remember how many record cold temperatures records were broken in interior Alaska 2012?  Lots!  

Not sure how you were measuring the temperature in the 60s & 70s but I doubt you experienced an ambient temp of -60 degF in the Kink-Matanuska River area.  Perhaps -55 degF in some localize area with temperature inversions, but not -60 degF.