The lowest temperature for outside painting is 50 degrees Fahrenheit. If it is colder than that, the paint will not adhere properly.
Excessive cold causes paint to thicken, so it will not go on smoothly, and it won't flow into cracks and crevices. Cold paint can get lumpy. Paint will not dry the way it is supposed to if the temperature is too low, since it needs the warmth to make it set up. Cold air means paint will not absorb into the material it is supposed to bond with, such as wood or metal. The ideal outside temperature for painting is between 50 F and 90 F. Temperatures above 90 F can bake paint instead of drying it properly.