Are aero road helmets too hot for summer riding?

It depends on the specific model and your heat tolerance. Early aero road helmets were notoriously hot, but modern designs with effective internal channeling have narrowed the gap significantly. In temperatures above 28°C, most riders will notice the reduced ventilation, especially on climbs where airspeed drops. For hot summer riding, a standard road helmet remains more comfortable, and many racers switch between the two based on conditions.