WHY ARE MY WINDOWS LEAKING IN THE WINTER?

My windows are leaking, but it isn't raining! Well, your windows are probably not leaking, but rather are "sweating". The moisture you have observed on the windows is actually condensation. This results from cold window frames in contact with moist indoor air. If the windows are non-thermally broken, the metal is cold and will cause condensation. Should you not be able to replace the windows, crack them a bit to let in some dry air. It will cost energy, but you will get fresh air and skip the cost of window replacement.