The perfect environment for using polyurethane is 70°F. This will ensure drying times don’t become too long. If the temperature is as low as 55°F, it can cause water-based polyurethane to form a texture that resembles orange peel. With oil-based products, lower temperatures aren’t too problematic but will slow down oxidation processes. But you can still work in temperatures as low as 60°F. If you work in much higher temperatures, the layers will simply dry quicker, especially with water-based polyurethane.