“Hair does not grow quicker in winter, at least not on humans,” says John DeSpain, a dermatologist at DeSpain Cayce Dermatology Center & Medical Spa in Columbia, Missouri. “Some areas do grow faster, but the rate of growth is fairly constant year-round.” Head hair, a fairly consistent baseline, grows at the same speed—about 1.25 centimeters per month—all over your head. “I suspect leg hair is about the same as the scalp,” DeSpain says.
DeSpain is a member of the American Academy of Dermatology, which does not have an official comment about seasonal hair growth. “I took a quick look through the literature and found very little scientific research on this topic,” says Allen McMillen, manager of research and liaison support for the Academy. McMillen did, however, pass along an abstract for the 2009 study “Seasonality of Hair Shedding in Healthy Women Complaining of Hair Loss.”
For six years, researchers in the Department of Dermatology at University Hospital of Zürich in Switzerland questioned whether hair shedding reflects seasonal changes in human hair growth. “From this abstract, we can gather that the most hair was shed during the summer and the least hair was shed during the winter,” McMillen says. “A sweeping generalization should not be made based on this single study, but there is evidence to suggest there might be seasonality of hair shedding.” So, if you feel like you’re constantly shaving in the winter, it’s likely because you’re shedding less hair—not that you’re growing more.