Heat Rash in Babies Summer can be challenging for babies because their delicate skin is highly sensitive to heat and humidity. One of the most common skin problems babies experience during hot weather is heat rash. Also known as prickly heat or miliaria, heat rash develops when sweat becomes trapped under the skin due to blocked sweat glands. This often leads to tiny red bumps, irritation, itching, and discomfort. Babies are more prone to heat rash because their sweat glands