You need to look for "High-Twist" Wools or Open-Weave fabrics (often called Fresco). Unlike standard suit wool which traps heat, high-twist wools are woven with gaps that allow air to physically pass through the fabric, cooling your skin.

• Alternative: Linen-Wool Blends. Pure linen wrinkles aggressively, which looks messy in photos. A linen-wool blend gives you the "breathability" and texture of linen but the structure and drape of wool, ensuring you look sharp at the altar and at the reception.
• Construction: Ask for "Soft Tailoring" or "Half-Lined" jackets. This removes the heavy internal padding and lining layers, significantly reducing the heat retention of the jacket.