 No one looks forward to painting the outside of the house. So if you're looking for excuses, check the weather forecast. Poor weather conditions can cut a day of painting short and ruin what you've already applied. Uncured paint will blister and swell in rain and even in high humidity. And although most of today's exterior paints are fast drying, they still need time before getting rained on. Oil-based paints need even longer time to cure. It's best to paint when the temperature is between 50 and 85 degrees.