Sweltriest is an adjective that refers to a hot and humid climate or weather. Some antonyms of sweltriest could be chilly, cold, cool, crisp, and refreshing. When the weather is cold, it means that the temperature is low, and there is little or no humidity. Cool weather is more moderate, not too hot or too cold. Crisp weather refers to low temperatures with less moisture in the air. Refreshing weather is associated with cool winds, low humidity, and a good atmosphere for outdoor activities. All these antonyms of sweltriest depict weather conditions that are pleasant and not too harsh on the body.