a dry aid (low humidity) day, front moving in later that night, high winds, forecast for big temp changes - I like very windy days, deer move a lot it seems, they aren't comfortable staying in one spot, they can't see you move as well either and the wind is very predictable

or 2nd / 3rd week of october, after its been dry for a few weeks and right after a rain - that REALLY gets the bucks to the scrapes to freshen them up