What Causes Condensation on Windows
Condensation on windows occurs because water vapour in the air deposits itself on surfaces that are at lower temperatures.
When warm moist air meets the cold glass surface of your windows, it releases some of this moisture onto the glass as water droplets. This is condensation.
In most cases, internal condensation issues occur because of too much humidity in the room or little to no air circulation. Low internal room temperatures can also make problems worse because surfaces will be cooler which creates a bigger temperature difference with the air and allows more water to condense.