Spray painting requires understanding the weather as much as it requires technique. Temperature and humidity are the two variables that cause the most paint failures.

Temperature: most urethane and lacquer topcoats have an application window between 65°F and 85°F. Below that range, the paint doesn't flow properly and dries too slowly, creating sags. Above that range, the paint dries too quickly, creating orange peel.

Humidity: high humidity causes blushing in lacquer (a milky haze caused by moisture trapped in the film) and can cause adhesion problems in urethane. The humidity should be below 65% for reliable results.

The practical solution: spray in a heated, conditioned space. A paint booth is the correct environment. A warm garage with good airflow is the minimum acceptable alternative. Check the conditions before you mix paint.