As people ready their homes for spring they often want to know how warm it needs to be to paint outside. The quick answer you often hear is 50 degrees. That’s true for the majority of latex paints, but that answer can be deceiving.
What the thermometer says when you apply the paint matters, but what the temperature does over the next 24 to 48 hours is just as important. In the spring and fall, daytime and nighttime temperatures can vary widely so dew forms on the surface easily in the cool night air. Even though paint may dry to the touch in a few hours, it’s still curing for hours and hours. When this moisture gets into uncured paint film it causes some of the ingredients to come to the surface when the moisture evaporates. That can lead to surface staining and adhesion problems.
Even if the paint looks fine, its life expectancy will likely be shortened. Check the paint label. If the forecast calls for temperature to drop below their minimum temperature with a day or so of painting, wait! Or look for a paint that can applied at lower temperatures.