We do have cold winters but that does not mean we have high humidity indoors. Relative humidity means the water contents of the air at 0 degrees is very very lo

We do have cold winters but that does not mean we have high humidity indoors. Relative humidity means the water contents of the air at 0 degrees is very very low. The higher temperature, the more moisture the air can hold. So when you heat up the air the same amount of water shares a much lower percentage of what the air can hold. In winter the hygrometer is showing 100% moisture outdoors (because ours can't measure below zero degrees C). When that air is heated up indoors, it holds about 20% of what it can hold [0], most likely thanks to warm water taps, us breathing and other moisture sources. This is why many people run their humidifiers so they can at least have 30-40% in winter. Less dry, cracked skin and nose bleed. [0] https://en.wikipedia.org/wiki/File:Relative_Humidity.png https://en.wikipedia.org/wiki/File:Relative_Humidity.png