Actually Sept. is best for calling because bulls are testing each other out for the soon to be prime rutting coming up. Oct. is hardest calling due to the rut and the bulls are with the cows.. Warm weather or not that bulls will be moving during that last week of Sept. They are establishing territory and the bull grunt is best then. The key thing is being able to wait where you are calling. With only a few days to get one that can be the hardest part of it. Early morning and evenings are both great but do not stop. They move when they want and will move during broad daylight regardless of temps. Around water holes is the best even if it is just a small bog cows will hang around those areas and the bulls will not be very far away.. Good Luck to you..