According to biologist - take it for what's it's worth - deer rut or their instincts tell them it is rutting season by the length of daylight. As the days get shorter the internal clocks and systems take over.
They say that the beginning and end of the rut season will never vary more than a few days no matter what the weather.
Many times we say that deer won't move when it's warm. Again, according to biologists, by this time of year, the deer coat is thick and works as an insulated against cold and heat and what we have seen for weather isn't a factor in whether or not the deer move - I'm not sure I can black and white say yes, I agree with that.
Deer have habits - feeding, mating etc. Generally speaking, when we find deer that seem bunched together, it is usually because there is limited food sources and deer will move between bedding areas and eating areas. When there is an abundance of food, deer can scatter out and seem sparse to us.
Bucks will always be on the move during the rut - warm or cold. When the urges are there, rain, snow, sleet, cold, hot, whatever ain't going to slow them down - sounds like the friggin mail man.
My two cents worth and 43 years of hunting experience. Does that make me an old timer? Nah!