A couple different cold-weather factors contribute to there being just too much fluid for the nose to hold (gross, I know, but true).First, because winter air tends to be very dry, the nose has to produce a lot of extra fluid to humidify it properly on its way to the lungs. Sometimes it makes so much that it runs right out the end of the nose.What’s more, when that warm, moisturized air gets breathed back out into cold, dry surroundings, it condenses on the cold tip of the nose, adding even more fluid.