It's time to paint the interior of your home, so pick the optimum moment to tackle the ceiling, walls and trim. Weather, climate, temperature and light all affect the outcome of the job and how much it disrupts your life. But you have a far wider latitude indoors than out; weigh convenience against conditions before you break out the brushes.
Winter, Spring, Summer, Fall
Indoor painting is a year-round pursuit. Interior paint dries best between about 50 to 85 degrees Fahrenheit, so avoid painting in extreme temperatures. Warm the crisp cold air of winter with a heater to dry paint faster; you don't need all the windows wide open to eliminate paint fumes. A well-ventilated room and no-VOC paint will take care of smells and toxic chemicals. Brisk weather in spring and fall means you can throw those windows open, and the longer daylight and breezes will help speed the job. Summer gives you the most sun and the longest natural light to paint by. But the heat can make it unpleasant, and summer thunderstorms will slow things down. The good news is you're under shelter, and, if you can close off a room while it's a work in progress, you can pick and choose your season.
Storm season or the rainy season are the worst times to plan a painting party. The humidity in the air keeps the paint wet longer. Because the paint is slow to dry, you can't apply a second coat or a finishing coat as quickly. You may tie up a space for several days between coats, and you can't rush it. Slap that second coat on too soon, and you will ruin the adhesion of the first coat, destroying the film that isn't set yet and preventing the second coat from sticking as well. If you're painting furniture in humid conditions, you'll have to let the paint cure or harden for a longer time before placing anything on the finish. Try a dehumidifier or an air conditioner to remove moisture from the air, if you have to paint when it's humid.
When you're the painter, get an early start as soon as it's fully light, so the primer or base coat has time to dry, and you can apply the final coats of paint all in the same day. When you're hiring a contractor, consider scheduling the job in winter when painters are least busy. A pro may give you a discount in the slow season, and will work with your schedule, not pencil you into a backlog of jobs.
In addition to the odor-free health benefits of no-VOC paint, most brands have very good coverage -- you may not even need that second coat, so you'll save even more time.