To everything there is a season, and the season for painting the outside of your house isn't winter, unless you live in a moderate climate. Even if you do, or if you live in the north and must do your outdoor painting during the warmer months, it's important to choose a good day for the job. Working on the wrong day can lead to problems such as flaking paint, runs, cracks and bubbles.
It goes without saying that you should refrain from painting your house when a storm is brewing: Rain falling on wet paint creates a runny mess, even if the paint is oil-based. Moisture from the air can also settle on days of high humidity, though, even if the weather report isn't calling for rain, which can make the paint bubble. Moreover, moisture develops when the temperature fluctuates over a wide range from day to night. To avoid dew from ruining your paint job, you should make sure that you apply the last brush load at least four hours before the temperature falls low enough for it to develop.
Not Too Hot, Not Too Cold
Painting in extreme temperatures is a bad idea, whether they are high or low. Paint dries too quickly in high temperatures, especially when the humidity is low, which can cause it to shrink and crack. If the temperature is too low, on the other hand, paint doesn't dry quickly enough, and even if it doesn't run, it may remain tacky for a day or two -- long enough to pick up debris from blowing winds. The minimum recommended temperature for exterior painting is 50 degrees Fahrenheit unless you're using a product designed for cold weather. The minimum application temperature for these products is 35 degrees Fahrenheit.
The Season for Painting
The best time of year for painting depends on your local conditions. If you live in a northern climate, and you get snow, it's best to wait until late spring to paint to give your house time to dry out. One Boston painter waits until June before starting any exterior project. Summer brings with it calm days and warm temperatures, but it can also bring wind, and it's best to avoid painting when it's windy. Wind carries overspray from your paint sprayer far and wide; it pollutes your painted surface with dust; and it could even knock you off your ladder.
If you're planning to paint your house, check the weather report daily. The best day to paint is one during which the temperature is expected to remain moderately warm -- between 50 and 85 degrees Fahrenheit -- and little to no wind is in the forecast. If you're using oil-based paint, you'll get good results between 40 and 90 degrees Fahrenheit. Partly cloudy to cloudy weather is better than sunny weather, because sun can warm the painted surface and cause cracking. The temperature should stay above the dew point at night, and, ideally, the forecast should call for stable conditions for one or two days to give the paint time to cure after you paint.