Correct me if I am wrong but I always heard and seen for myself that in the winter time the 2 worst things are MUDDY WATER and CURRENT (Current would be caused by a big rain or rise in lake level)
If the water is usually clear and suddenly gets muddy then that is the worst thing especially with it being cold. I believe the fish go into shock and it takes them some time to adjust to the new water color.
If the water is normally always muddy, then the fish adjust and I seem to do good even if it is cold.
I really feel that the muddy water (when it is usually clear) is one of the biggest ways to kill a bite no matter the time of year. The current doesn't help but the fish can adjust to current and get out of it. A lot of times in the creeks, the fish cant escape from the muddy water.