Humidity can cause damage to various types of Diwali decorations. For instance, paper-based decorations may become soggy or lose their shape, while metallic items like diyas and lanterns may tarnish or corrode. Rangoli designs made with powdered colours can smudge or fade due to moisture in the air. Additionally, fabric-based decor may develop mould or an unpleasant odour if exposed to prolonged dampness.