We always think about hydration in the summer, but actually, for our health, it's even more important to drink enough water during the winter season. Shockingly, 75% of people are dehydrated during the cold weather months and most of us don't know it, experts say. The colder weather and more arid air and indoor heat all combine to create a condition in which people are chronically dehydrated, which compromises their ability to fight infection, according to the latest research. In winter you are more likely to forget to drink because, in the absence of heat and perspiration, you have no idea that you are in a constant state of mild dehydration. The fall and winter are the most important seasons to hydrate, according to experts, to support your immune system and give your body the ability to fight off infections, and flush out toxins via urination.