Winter weather, particularly hard water and cold, dry air, can disrupt the scalp's natural ecosystem, leading to dryness, itching, and hair fall. Hard water leaves mineral residue that interferes with the scalp's moisture barrier, while cold air accelerates moisture loss. Dermatologists emphasize that maintaining a healthy, mildly acidic scalp pH of around 5.5 is crucial for supporting the skin barrier and preventing microbial issues. Alkaline shampoos and environmental factors can further compromise this balance.