A lightweight, breathable shirt made from a natural fabric like cotton or linen is typically the best option for summer. These materials allow air to circulate and help to wick away moisture from your skin, keeping you cool and comfortable even on the hottest days. Additionally, shirts with lighter colors can help reflect sunlight and keep you feeling cooler. Avoid thick, heavy fabrics like wool or polyester, as they can trap heat and make you feel uncomfortably warm. Short-sleeved or sleeveless shirts can also help keep you cool, although it’s important to protect your skin from the sun’s harmful rays by wearing sunscreen or covering up with a hat or lightweight long-sleeved shirt when necessary.