Best time is when your kids are old enough to help but have not moved out yet! Just kidding. Here's what we do:

Not too hot - paint sets too quick when it is hot. As a Ben Moore rep once told me - today's paint is the most complex chemical formulation you can buy without a prescription. When it is applied to the wall, there are agents that are drawn toward the surface to create the bond, others that are pulled toward the air to create sheen and durability, while others protect from freezing, drying too fast, hide things underneath, create the color, provide elasticity, etc... Try to paint when it is under 80 - 85 degrees if at all possible.

Chase the shade - paint on the side of the house that is in the shade, then try to follow that around the house. The longer you can keep the paint wet (or "open") on the surface, the better the various chemicals in the paint have time to do their thing.

Watch for rain - don't apply any paint if rain is expected within the next 24 hours. Paint dries outside in - the surface may look and feel dry, but it can stay wet inside for long after sunset. Getting water on there during this period will make things ugly.

Watch for cold - I do not let our crews paint if it is going to be below 50 degrees overnight. You can do this (Sherwin Williams has a paint that will go to 35 degrees), but since I am paid to do the best job possible for my clients, we won't paint when it is going to be chilly. The setting process of the paint slows when it is under 50 - again which can lead to problems.

Start out back - If you are doing it yourself, starting in the back yard will keep you motivated to finish the front!

General guidelines - paint will not stick to dust, or raw wood, or flaking paint, so clean, clean, clean. We powerwash one day, then come back the next and start sanding and scraping anything the powerwasher did not get off. Then repair wood as needed, prime (primer will adhere to raw wood), caulk all gaps, then apply two coats of paint. (In my opinion, Sherwin Williams Duration is the best.) Lastly - and before doing anything, check for Lead based paint and take precautions if you find it. (Go to www.epa.gov for fun reading on lead paint!).

Now, having said all of that - if you are thinking about the sequence, paint versus roof, I always do Roof first!

Best of luck!
Robert

Thank you for the information regarding the painting of our house!

Weather plays a big part in exterior renovation / building.