Temperature is critical when it comes to painting – especially when you’re painting exteriors. Paint relies on air temperature for proper drying and curing. Even if the high will be 60, that still means that the temperature will be lower for the rest of the day. The good news is that some paint manufacturers have come out with lines that extend the painting season. These new paints can be applied at much lower temperatures (down to 35F) without running, bubbling, peeling, flaking, or fading.
That said, painting exteriors in fall and winter can be a dicey proposition. You need to be sure that temperatures will remain within the acceptable manufacturer application recommendations for at least three hours, if not more. And even if the paint will dry and cure, there’s a chance that other necessary materials like caulk, fillers, and primers won’t work quite right. Keep in mind, too, that temperatures can change quickly in the fall and winter months. If you have to paint outdoors try to work between 10am and 2pm on a day that there’s no possibility of rain. Stopping early in the afternoon gives paint time to begin developing a moisture-resistant film.
Dew is another issue – especially in fall when nighttime and daytime temperatures are very different. When dew settles on paint that hasn’t had sufficient time to dry, it becomes patchy or blotchy because moisture is trapped under the paint film.
A second coat? May trap moisture in the first so allow plenty of extra drying time between coats if you have to paint in colder weather.