The best chances of forming a strong hurricane include: Warm seas, high moisture in the air, and calm upper winds.
Hurricanes generally require warm ocean waters (at least 26.5°C or about 80°F), sufficient moisture (humidity) in the atmosphere to fuel the storm, and relatively calm upper-level winds to allow for the storm to develop and strengthen. Strong upper winds can inhibit development by creating shear that disrupts the organization of the storm.