Hunters misinterpret the rut.. The rut happens the same time, the weather factor ur talking about has to do with how vocal they are during the rut, not if they are in it or not... And if there isnt a lot of competition between bulls (due to the lack in numbers) then you wont hear to many bugles.
Heres a list of what i believe to be the biggest the factors if the bulls are bugling or not... 1 being the greatest.
1. weather
2. competition
3. surroundings/location