Mature whitetail bucks are wearing winter coats by mid-October. They overheat fast in mid-day temperatures above the mid-50s and shift activity to dawn, dusk, and night to cope. A cold front that drops the high from 60° to 38° during peak rut is the difference between a slow week and the best hunting of the year.
This is why "rut week" weather forecasts matter so much. Pick sit days from the cold half of the forecast band, especially the day right after the front clears. State rut dates locks the calendar window; weather selects the day.