Yes, a car seat blanket can be used in warm weather, but it is essential to choose a lightweight and breathable material. Look for blankets made of materials like cotton or bamboo, as they are lightweight, soft, and breathable. You should also avoid wrapping your child too tightly in the blanket, as this can cause them to overheat. Instead, use the blanket to cover your child's legs or shoulders, leaving their arms and upper body free to help regulate their temperature. Always monitor your child's body temperature and remove the blanket if they show signs of overheating.