Believe it affects the burn primarily due to draw resistance and over time affects the flavor.
Humidity too high and the draw is tough and hard to keep it lit.
Over humidified sticks also seem to have less taste. - something along the lines of how a dry aged steak is better than a fresh cut steak. If it is too moist, the cigar has to overcome the excess moisture before the flavor profile comes through.
Temperature not as much of an issue as long as it does not get high enough to have a beetle hatch
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