I can relate to the 100°F outdoor temperatures, as long as you make sure to include the humidity. If the equipment is located remotely (in a closet, for example), I am wholeheartedly in favor of mechanical ventilation - preferably in conjunction with good natural ventilation (or a backup mechanical system) to keep things from cooking if a fan dies. But unless you lose air conditioning while still having power and running your equipment, those 100+ temperatures won't ever reach the rack. They will make it harder for your AC system to reject the heat generated by the equipment (the AC system will be coping with a "design day" with the building envelope loads at their maximum and every internal load will add to that), but that's true whether there are fans in the rack or not - unless you put a dedicated AC system in the rack, including a dedicated outdoor condensing unit.

The reason I prefer natural ventilation in an equipment rack that is located in the listening/viewing room is ambient noise. Fans - even quiet fans - are going to generate noise. A good natural ventilation design can prevent stagnation, and it can do it without adding background noise. Added bonus: natural ventilation isn't subject to burned out motors like ventilation fans are.