Pat, pat, pat. Scratch, scratch. Lemme just stick that bobby pin right...there. You've been scratching your head trying to figure it out. Why is your scalp so dry? When the seasons change, our hair can, too. Drier air in winter and sweltering temps in summer can dry out your scalp. Each day, the skin on your head is making room for more new cells, causing the old cells to slough off and leave you with itchiness and flakes.