Cold fronts and an ensuing high pressure system will make for a tough bite, winter or summer.
However, my personal opinion is the biggest factor that negatively affects the ice fishing bite is the amount of snow and light penetration.
As the ice season gets longer the bite often gets tough when there's a heavy snow pack that inhibits light penetration. It's for this very reason that first ice and last ice is often the best.
In the dog days of winter, usually Feb, oxygen levels are depleted, light penetration is diminished and the fish seem to be almost lethargic.
Could be simply coincidence that these dog days coincide with super cold temps....it's usually pretty cold in the middle of winter.