When looking for the best replacement windows for Arizona heat, consider the following factors: 1. Energy efficiency: Choose windows with Low-E glass and multiple panes to reflect heat and UV rays, keeping your home cooler. 2. Durable materials: Opt for windows made from materials that can withstand extreme temperatures, such as vinyl or fiberglass. 3. Good weatherstripping: Proper weatherstripping helps prevent drafts and maintains a consistent indoor temperature. SI windows, with their energy-efficient design and durable vinyl construction, can be a suitable choice for Arizona heat.