Warm and dry beats cool and damp
Unless your shop stays a constant 72 degrees, temperature and water vapor will affect your finish. Problems range from spray lacquer turning cloudy because of moisture vapor entering the finish to water-based finishes drying too quickly in arid climates, trapping bubbles and brush marks. If possible, postpone finishing until a day when nature cooperates. Otherwise, coping strategies for less-than-perfect conditions include warming your shop in the winter while a finish dries. (Just avoid exposing combustible fumes to open flames or heat sources.) In dry conditions, steam vaporizers and humidifiers adjust indoor humidity to optimum levels. To apply lacquer in mildly humid conditions, add a retarder to spray finishes or use brushing lacquers that dry slowly enough to prevent the finish from clouding.