Weather
Weather can have a profound effect on psoriasis [5]. For some people, a change in weather causes their psoriasis to flare up. Cold weather in particular can trigger psoriasis because people have less exposure to sunlight and humidity. Hot and dry indoor air can also contribute to a flare. In addition to direct weather factors, cold seasons tend to increase the incidence of respiratory illnesses, which are also psoriasis triggers. Warm weather may be good for psoriasis because there is more exposure to natural sunlight and the air is more humid.