While it is ideal to paint your home in dry, warmer weather, it is not always possible. Fortunately you can still paint your home even if the weather is cooler, but there are some precautions to take. Ideal cold weather temperatures for drying are 50° F or warmer during the day and 35° F or warmer at night. You should also only paint when it is dry, since fog, rain or snow can damage the new paint, causing discolouration and other problems.
Purchase a "cold-formula" or "low-temp" paint. These paints are formulated specifically to be used in cooler temperatures.
Wait for an appropriate day. Unlike other seasons where you can paint on virtually any day, during colder months you need to pay extra attention to the air humidity and moisture levels. Don't waste your time painting on damp days since you will have to repaint it. Wait for a day with temperatures above 50° F. At night the walls of your home should not get colder than 35° F, so ideally you should wait for night time temperatures of 40° F since the walls can chill and get colder than the ambient temperature.
Pay attention to the location of your home. The south facing wall will probably receive little light or heat so it may be a great deal colder than the rest of the house. If you live in a dark area, such as under large shade trees, you may also have localised ambient temperatures that are much lower than other parts of your town. Use a thermometer to get an accurate localised reading.
Paint your home just as you normally would, although you should wait until around noon, when the walls have had time to warm up from the night temperatures. Cover window seals, light fixtures, and any other parts that you do not want painted with painters tape. Caulk holes and cracks and sand them down. Use a paint roller to apply low-temp primer and wait for it to dry (this may take a day or more so be prepared to paint the next day). Paint the walls using a painter roller for large spaces. A 2" flat brush should be used to paint cracks, corners and around things that need a more delicate application, such as light fixtures. Wait for the first layer of paint to dry (possibly overnight), and then apply a second coat.