When it gets colder outside, the air pressure in your tires will decrease a pound or so for every 10 degree drop in temperature.
As a result, your tires will have more of a chance of developing something of a flat spot after sitting overnight in the cold. That flat spot becomes pretty evident once you start driving, but after a few miles, the tires warm up enough for that "flat spot" to go away and the tire to feel smooth again?
I don't know that this can be TOTALLY counteracted even if you maintain the correct tire pressures when it's cold, but the closer you DO maintain them to proper operating pressure (32 psi - or whatever the recommend factory pressure), the less pronounced such flat spots will be and the sooner any associated vibrations will go away once the tires have warmed up from driving.
Just a theory of mine anyway.