Is 50% humidity too high in winter? For most Alberta homes, yes. At 50% indoor humidity, condensation forms on windows and other cold surfaces once it drops below freezing outside, which can lead to mould and water damage around frames and walls. Some online advice still recommends 40–60% in winter, but that’s too high for our climate. Sherwood Mechanical explains safe winter humidity levels for Sherwood Park homes. Find out whether 50% humidity is too high in an Alberta winter.