Humidity & Mold in Boston
Boston, Massachusetts sits in a humid continental climate averaging 67% relative humidity. Here is what that means for your home — and the products that actually help.
Quick answer
In Boston, keep indoor relative humidity between 30% and 50% (EPA guidance). A 30–35 pint dehumidifier covers most rooms up to 1,500 sq ft; a 50 pint unit with a continuous drain is better for basements. The most frequent local problems are old-basement dampness, ice dam leaks, attic mold.
Top moisture issues in Boston
Best dehumidifiers for Boston
More in Massachusetts
Boston humidity FAQ
What is the average indoor humidity in Boston?
Boston averages about 67% relative humidity (Humid continental climate). Keep indoor levels between 30% and 50% RH, as recommended by the EPA, to limit mold growth.
Why does mold grow so easily in Boston homes?
The most common local drivers are: Old-basement dampness, Ice dam leaks, Attic mold. Mold needs moisture, an organic surface and stagnant air — controlling humidity removes the first condition.
What size dehumidifier do I need in Boston?
For a damp room up to 1,500 sq ft in Boston, a 30–35 pint unit is usually enough. For a wet basement or 2,000+ sq ft, choose a 50 pint model with a continuous drain hose.
